Wonder if anyone can help out there.
I recently fitted a new aftermarket Clarion haed unit (double DIN) into my 55 A3 TDi Sport. Looks and sounds lovely. After a lot of hassle with the wiring harness and getting power to run and remember presets, EQ etc etc, it all works fine. However, it wasn't until a few weeks later, that i went away for the weekend, and the car wasn't driven for at least 48 hours. Upon my return, the headunit has reset to factory settings, so i needed to change colours, EQ, add presets all again!

I originally thought the battery may have shorted or something... but it's done it twice since, when i've not driven it for 48 hours or more.

Very puzzling. As i say, the mods i had to make to the wiring harness were to run a +ve cable from ignition, then 'share' the power supply cable onto the aerial power cable... Why does it forget after 2 days?