My wife and I had gone to a rather glitzy gallery opening in Unit 26. It was something of a dynastic show; two out of the three young artists exhibiting their work have well-known artist parents. Eric's daughter Clea Van der Grijn and Camille's daughter Michele Souter showed alongside Tom Climent's work. After the reception a meal seemed a good idea and since Fairview was just up the road and Clontarf not much further on, I thought we might try the Italian restaurant called Picasso that I'd heard about there. Not being quite sure where it was I asked directions from Gerry Ryan who knows it. 'Take the coast road and turn left after the third church,' he told me. There used to be jokes about Irish directions based on churches and pubs, but they work perfectly and we found it easily enough, just off the coast road.

The restaurant is on two floors and although we arrived with no reservation we were greeted warmly and shown to a table upstairs. The menus are nicely presented and the wine list, although short, has plenty of good Italian wines and a sprinkling of French and New World. I found a good Vino Nobile di Montepulciano by Bigi on the list and ordered it. When the bottle came it was flashed before my eyes and the waiter started to open it. 'Wait a moment,' I said, 'that's not the wine I ordered.' 'It's a better one - look it's a Riserva.' True enough it was, but I prefer to be told when a wine has been substituted with a different shipper.

I looked down the menu and was a little surprised by the prices. Most starters were between £5 and £8, pasta dishes were all over a tenner, some up to £13, main courses up to £18. For this sort of money I'd expect linen on the table and cloth napkins, rather than the paper that was before me. Still, I'd heard from my colleague Alan Stanford that the food was good, so I thought I'd reserve judgement. Susie picked the prawns as a starter and I wanted the Caprese salad, made with buffalo mozzarella. Increasingly I've noticed restaurants describing any mozzarella as buffalo mozzarella, so I asked the waiter if it really was buffalo. 'Yes, indeed,' came the reply, so I went ahead and ordered it.

With the arrival of the starters the evening began a downhill slide. What I had on my plate was indistinguishable from cow-milk mozzarella in taste and texture. I called the waiter and said so. 'I'll change it for you, sir, if you like,' he said accommodatingly. While I was thinking about this a second man came along, who belligerently took over. His manner was aggressive and brutish. He stabbed a finger at my plate. 'Are you saying I'm lying?' he bellowed. Before I could answer he'd gone, so had the waiter and so had my chance to change my starter. About five minutes later the second man stormed up to the table, slammed a Tetrapak down in front of me and walked off again. It said on the carton 'Buffalo Mozzarella' which proved conclusively that there was some in the building. What it didn't prove to me was that that was the cheese on my plate. I've driven 160 km round trips to the hinterland of Aversa in the Campania for no other reason than to buy buffalo mozzarella, I'm that fond of it. Apart from a different taste, it has a very different texture to the cow-milk variety. All I can say is this: if what I got was purchased by Picasso's in good faith as buffalo mozzarella, then they should change their suppliers.

So after this fracas we became 'the difficult customers'. Neither the waiter nor the second man came near us again. I know from my own days as a restaurateur that it's a temptation to stay away from people who you've decided are prickly or awkward, but it's not a great idea. Ideally you should never let discontent fester in a customer. But the fact is that I've been through this often enough and I wasn't prepared to let my evening spoil. We enjoyed the wine and we enjoyed two good main courses - veal for me and a fish platter for Susie, although no one came to ask were we enjoying it. A fresh-faced young man brought us our main courses, removed the plates and brought dessert menus. Susie wasn't keen on dessert but I chose the Tartufo Nero, not a black truffle, but a chocolately dessert which was perfectly pleasing. Two very good espressos finished the meal, and we asked for the bill.

While I was waiting for it to arrive I was wondering if my uneaten starter would be charged for. Probably it would, I decided. Imagine my surprise then, while looking down the bill, at finding I'd been charged not for two starters, but for four. I'll admit that I was a little vexed. If there was a table in the busy restaurant that night that needed things to go right it was mine. This kind of carelessness is guaranteed to make already disgruntled people apoplectic with rage. We went downstairs and found a man behind a bar next to a cash register. 'You've made a mistake here, you've charged me for four starters.' He looked at me, then at the bill, and then at the cash register. 'It's the machine,' he said, nodding in its general direction. He gave me a look and a shrug that implied this dumb piece of technology was entirely wilful, a rogue machine that added things on to people's bills for no particular reason other than its own perversity. 'It's the machine,' he repeated, while I awaited an apology.

Suddenly a new man arrived who seemed to be in charge. I explained the problem with the bill to him and he rang it up again. Meanwhile our first waiter and the second man arrived and they took up verbal cudgels with me. 'Are we dogs?' the second man demanded, perhaps rhetorically. 'You call me a liar? You want to step outside?' This last question took me a little by surprise - it's not a common method of dealing with complaints. It may be in the Dodge City School of Saloon Management Handbook, but most restaurants have more civilised solutions. I declined to join him outside, paid my revised bill which now came to £76.35 and added no tip.

'That wasn't very pleasant,' said Mrs. Tullio as we walked into the night air. 'I thought the food was rather good,' I said. 'Don't be obtuse,' she said, 'you know exactly what I mean.' The next day a note of apology and a hamper addressed to me arrived at the Independent's offices from Picasso's, which I naturally arranged to have returned to sender.