wheres the noise coming from? as the backup alarm in the boot will beep randomly when the battery is dying, but its not replaceable im afraid as the batterys are no longer available as company that made them has gone bust.
so either new one from audi for around £100 or disconnect which is what alot do including me lol.
there are ways to do possible fixes but only works aslong as acid from battery hasnt eaten the control board, which most do