About your only hope on this is if you didn't actually sign the work order in advance...or if you checkmarked *call with estimate* and they didn't call to let you know what the price would be.
If you just said fix it, looks like they can just act dumb and shrug their shoulders until you pay their price.
The last thing you want to do, at this point, is to bring in estimates, trying to shame/threaten them...maybe just give them a sad story and try haggling with them?
