Chiphead,
If I were You, I'd take it to the shop that has made the mistake and talked to them politely that they had made a mistake and what they should offer me as a possible solution.
No succes into it, them I'd move to another shop
to have it fixed and after it all I'd look for my rights if a considerable amount of money were involved in the repair.
I work here assembling engines in a commercial level. I do a lot of machine service. And I have used over the time 4 or 5 machine shops in different cities where I lived thru the years. And in the shop I take my parts to be machined nowadays I use to act this way:
1- I use to explain to any employee that I do know how He does his job, and I trust him my parts and so I like to measure all the jobs I have done there in front of the guy who has done it.
2- Normally at a first glance they do not like it. After it is done and I check it out ok, the way i asked it to be, I use to hand him a tip.
Also, at X-mas time, I do take a box full of wine bottles and hand to all the guys in there.
3- Of course as I use to hand into the shop a ridiculously big amount of parts to be machined, they use to look at me as a big and important customer. But the way I use to deal with the employees and the shop managers normally helps me a lot in getting a decent job almost all of the time. And if occasionally I do not get what I want I use to talk it out normally, and get it fixed, at no charge.
Been working with the shop for almost 2 years since I moved to Brasilia and no complaint about their job. And as an added bonus, I do not pay the same price other customers have. They do offer me 30% off the reg price and always offer me at least 30 days to pay even with the discount. Needless to say I love working with them. And I have to admit that they do have it the same way!
