Is there any sort of sweetener you can fob them off with (if you know what I mean), at the end of the day its all about good customer service and technically its not for the customer to know about background issues, even though they do occur and are out of your hands, I know the job is getting done alot cheaper, but they dont really care about that do they!!
See if you can give them a free car wash or something that they would appreciate that aint going to cost you an arm and a leg - obviously this is just a thought.
Guess thats one way of not getting a bad rep, as you are turning a bad situation good, just with a little touch.