Do I have to pay for a repair bill if only a verbal agreement was made?

My car stopped working (battery seemed to have died, tried to jumpstart, and buy a new battery to no avail) so I had it towed to a nearby shop, I signed for them to do a $100 diagnostic and they held it overnight. They called to tell me a belt broke and had to drain the freon, coolant and some other stuff to repair and gave me an estimate of $163.02 in the way that he worded it (He didn't use the notation of hundred, thousand, or cents) later he called to tell me the 2 bolts were turning into dust and the new estimate would be $170 something... assuming he was still in the hundreds range I gave him the ok. I started to get worried about the confusion and found out he was talking thousands. Since I did not sign anything but for the diagnostic, and he wasn't clear on the price can I dispute the bill?