It's called the asshole tax, and it's what happens when you believe a child over the person you're paying to fix your/their mistake (again).

Having run my own computer repair side business for a while, I would have (and have) absolutely done the same thing in the situation. I also had repeat fliers that realized their mistakes and didn't try to blame me for their failure, and the nicer ones even got a discount. But the asshole tax is there to make dealing with problem customers more worth it, and potentially to encourage them to find someone else to torment and give money to.