Parking sensor tone

Hi,

Dad's got a 2005 Octavia Elegance, a few months ago he was rear ended and the bumper had to be changed. Before the accident the parking sensor tone was a nice 'beep' sound but since changing one sensor in the bumper & the command module but now the tone iscompletely changed and really annoying.

According to the main dealer they can only change the frequency of the tone and not the tone itself, surely they can set it to the tone it was before???

Any ideas welcomed!

Jon