1/ As a fitter if you damage a pipe you fix it in your own time.
2/ Pipes in concrete/render should be wrapped as cement attacks copper.
BUT plaster doesn't harm pipes.
Whether it's worth doing the work retrospectively is another matter.
If it were my house I wouldn't have that plumber back anyway, I wouldn't pay his bill, when he sues I would put in a counter claim and get estimates to puyt right the damage he did. The reason I would take this strong stance is because he tried to bully you at the beginning (claiming you had to pay his and two layabouts wages while he waited for you to decide to spend a fortune because one of his layabouts put a cold chisel through your pipe). You don't want a bully in your house.
He won't take you to court if you stand up to him. He hasn't a leg to stand on in court.
2/ Pipes in concrete/render should be wrapped as cement attacks copper.
BUT plaster doesn't harm pipes.
Whether it's worth doing the work retrospectively is another matter.
If it were my house I wouldn't have that plumber back anyway, I wouldn't pay his bill, when he sues I would put in a counter claim and get estimates to puyt right the damage he did. The reason I would take this strong stance is because he tried to bully you at the beginning (claiming you had to pay his and two layabouts wages while he waited for you to decide to spend a fortune because one of his layabouts put a cold chisel through your pipe). You don't want a bully in your house.
He won't take you to court if you stand up to him. He hasn't a leg to stand on in court.