I hate hearing these sorts of stories, the customers may as well be stealing from you.
I know I have had to pay for things in the past where it's ended up costing me more than expected and i have felt a bit ooooh didn't expect that but I still paid, I had the work done that I asked for and it was my fault for not checking the price first which now I never forget to do. I would never dream of not paying unless I was blatantly ripped off which is usually obvious.
Your customer has not been ripped off and they are bang out of order.
I know I have had to pay for things in the past where it's ended up costing me more than expected and i have felt a bit ooooh didn't expect that but I still paid, I had the work done that I asked for and it was my fault for not checking the price first which now I never forget to do. I would never dream of not paying unless I was blatantly ripped off which is usually obvious.
Your customer has not been ripped off and they are bang out of order.