'03 Rav4 Trailer Hitch Wiring

[tenzyk]

Just had "U-Haul" install a hitch and wiring. Looked pretty nice for the $220 installation. HOWEVER, I checked out the wiring with the trailer and all lights seemed to be OK. BUT, when I went into Reverse, all Hell broke loose. There was a big clunk from the transmission and the vehicle was bucking like a bull. I disconnected the trailer and then discovered that the "Check Engine Light" was on, the Speedometer was inoperative, had no Backup lights and the power windows would not operate except for the drivers window. I checked the wiring and saw that the ground that was hooked up by U-Haul was the black wire coming from the Backup light. Obviously this is a no-no.

Has any one had a similar experience. If so, how do I convince U-Haul that they screwed up? Also, does anyone know of a common fuse that will correct my problems? I can't get an appointment with a Toyota service for 10 days, which means I can't drive in the rain since the windows are stuck open.

HELP!!!!!!!!!!!!!!