In September I had an expensive new, part bespoke, kitchen installed including a butler sink and a boiling water tap. The sink was supplied by the kitchen company. Recently we have discovered 2 or 3 hairline cracks emanating from the waste trap outwards, with more appearing. When the sink was originally delivered, I spoke to the kitchen company as it was not the same brand as on the invoice, although I think of a similar quality going by price. It had a big blue mark on it, and I was concerned it was a second. The kitchen company assured me it was not. When the cracks appeared I contacted them again and they claimed it was due to the plumber installing the waste unit too tightly. I asked them to go back to the manufacturer (Rak) with pics as the plumber has been fantastic and has had many years' experience, and I suspected the sink to be faulty. They said they had gone back to the manufacturer who also blamed the plumber for faulty installation. The plumber is coming round to look at it, but believes it most likely to be thermal cracking. I suspect the sink was faulty all along, but no one wants to take responsibility obviously. What would you do?