My dentist seemed like he was charging me more than he should’ve done, what do you think?

Q. Dear Dr Bohara, I am in need of your advice please. I had veneers done by an apparant top cosmetic dentist in London. When I had my teeth prepped and had temporaries on, I requsted some change. The dentist told me that if I wanted these changes done, that I would have to pay the full fee again. Bearing in mind that I was in temporaries and that no final veneers had been made, he wanted me to pay for the whole treatment twice. Can you please tell me if this is acceptable practice? To charge patients in advance for veneers that have not been made? Also, he made every effort to charge me extra and get me to spend as much as possible. When I was in temporaries for 2 weeks, he insisted that I needed to see the hygienist 3 times at an extra expense. When my finals were fitted, I immediately noticed gaps between the veneers and big black triangles. When I questioned him, he told me that it was my fault as my gums were in bad condition, yet when I saw the hygienist and the dentist himself before the finals were fitted, I was assured that my gums were healthy so he is trying to cover himself for the poor aesthetics. He then offered to fill the gaps and triangles at an additional cost, and told me I needed a gum graft. I feel he is simply using every opportunity to create errors so that I am forced to keep paying for them, yet I cannot understand how he could think to charge me again for the whole treatment when I was still in temporaries, then ask me to pay for him to fix the mistakes with the finals. iI would be grateful for any advice. He is not interested in anything other than money. Thanks very much,