Replacement of belt and tensioner

Had a vehicle towed into this shop for service due to breaking down on I81 heading to New Market. I never received a call letting me know what work was going to be done, what cost or when it might be completed. After reviewing the bill and checking prices for parts, it turns out they double the cost of parts for their repairs. I don't mind a company making a profit, this is what keeps them in business. However, I do find it extreme to try and make a 100% profit on parts. My advice to anyone getting service here, bring your own parts and keep a watchful eye on them for sure.