I contacted a plumber about the fact that my loo wasn't flushing very well and he came round a while ago to look at it and give a quote. It had a standard flush and he suggested getting a bigger flush and quoted to supply and fit that. I agreed and he did that yesterday. The loo is not flushing any better than before; if anything, weirdly, it's worse.
I texted him about it and he replied, politely and with technical explanations, to say essentially it's not possible for it to be worse (though it is), and that the reason it's not flushing better is that it has a compact cistern, so the only way to get improvement would be to get a new loo with a taller cistern.
He has sent me an invoice for the full amount quoted. Do you think I should pay it? I recognize that he put the time in to do the work. At the same time, it seems a bit rubbish for me to have to pay for something that has not improved the problem at all, and has made it a bit worse. If he had said initially that it needed a taller cistern then I wouldn't have had this work done.
He is a really nice and reasonable person, and I don't want to be adversarial about this. What do you think would be the fair and right thing to do?