Hmm, sounds like they sure did a shit job.
I'd try to leave all the ombudsman stuff unless it all gets really ugly.
I'd recommend getting the good bloke that you bought your car from to simply call and talk to them. If they still don't budge, maybe ask him to put it in writing.
I'd be wanting them to re-machine (providing they're now not going to be under the minimum thickness), or simply replace the rotors with brand newbies. (if you chipped in the extra, maybe you coul even get slotteds)
Good luck, don't let them F you over!