Poor customer service and overcharged!

GS left a message for us today. We will communicate our issues regarding their contracted service provider to them. We will update the forum after that time. To correct any misconceptions we accepted the $600 for the tire at the time it was quoted to us and accepted that this was the price for our mistake. What we dispute is the additional $215 we were told we owed for unauthorized service a day later. The same young man who came to do the tire work cut off the exhaust. GS Roadside told us he could do it and did not indicate any additional charge. It was not another person, trip or call out. We were told by GS roadside that he was authorized to do it. For what it is worth my husband does not recall that we were ever offered a tow to the nearest service center.