2011 A6 Avant Prestige Parking Assist No Warning Sound

[Alphapenguin]

My Audi was involved in a minor parking lot incident damaging the left rear lower panel behind the wheel well. The body shop removed the rear bumper assembly as part of the repair process and when I returned home post-repair I promptly backed into my garage door frame, learning only then the beeping proximity warning system was not operational.

Then, in the rear cargo area, I discovered a cable I had never seen before, actually tucked under the right cargo space adjustment rail, as well as a yellow wire, also previously unnoticed, extending the entire width of the spare wheel well.

Later learned the first mentioned cable is apparently for a trailer hitch hookup, that this car doesn't have, unless it's standard equipment, of which I was never aware, as I have no trailer hitch electrical hookup. Visit to my dealership confirmed the Parking Assist was malfunctioning, suggested the body shop never reconnected the parking assist cable.

So, where can I find that cable and connection, please?