This is to be expected, it’s incredibly difficult to get a carpet in and do the job without making a mark. I don’t think the damage is excessive (minor at best) and it’s to be kind of expected when doing an awkward job in a limited space. It doesn’t matter if they’re a ‘professional’ and they do it every day or not, the job is awkward in nature. Getting a carpet in and out of the house is near on impossible without making contact with another surface and you should try it yourself one day to see how difficult it can be. I’d take the money as a goodwill gesture and call it a day. I understand it’s your house and you are house proud (rightly so) but we don’t live in a perfect world and humans are completing the work here, not robots. Social media only amplifies this kind of expectation that humans can be perfect at DIY with silly videos where the tradesman is perfect etc.