but double cut either side of window ? really ! I was taught different to this, you're meant to be looking at tiles, not grout lines... I don't mean to be argumentative but I think we should put this to the vote we all know we can get paid on most jobs as the client doesn't look at tiling everyday, but.... if another tiler looks at your work, this is the benchmark as they can see right from wrong...
example: a client the other day wanted skirtings to match the courses on a 600x300 floor, one side 600 skirtings and 300mm on the left and right, I said this is highly unusual and persuaded them to have all 600mm skirtings, in the end they thanked me for my experience and the end result, I think we have a duty to point out potential irregularities... we get paid for our expertise, knowledge as well as manual skill..
ps: I think you should have been paid for it, as the tiling looks fine, and a setting out issue, does not warrant not paying
In summing up, the real issue is the tiler, not being as confident as he should be, stating the reasons why this and that would look better, clarifying it, and doing his job as a tradesman, as opposed to allowing an amateur to dictate the way the job went i'm afraid.