Same kind of experience, swapped my new Peach parts for their MB and NON MB parts and told me I was "crazy, those are the parts you gave us" and then I took out a photo of the parts laid out on my garage floor on a grey background and then used a blacklight to look for the UV paint marks I put on all the parts I gave to the shop for install.

The marks were not there.

I paid, disputed with my CC company, wrote the dealership with photo backup and filed a legal complaint with the NYS Dept of Motor Vehicles Repair Shop Licence Bureau and filed a legal notice with MB USA.

I got a full refund, they replaced the parts (which was returned to me a week after my omplaint in the original packaging) at no cost, they were fined $2500 by the State for fraudulent operations and work and I have never set foot in their dealership ever again. I also have a license plate frame that says "Ask me about Helms Bros MB Service" and I tell anyone who asks what crooks they are! I also dared them to sue me for defamation, they have declined as of yet.

BTW, MB USA NEVER answered my formal complaint...go figure!