CODING NEW DIFF SENSORS WITHOUT OLD SENSORS

[KARBON]

Hi I am new to the forum and was looking for some advice, I have a 2014 RS4, just spent 3k on drc repairs and had diff sensors replaced. The mechanic I had thought that the new sensors had to be done by main dealer but it turns out he binned old sensors. I now understand that the sensors are specific to the diff and the old sensors are needed. Main dealer are suggesting I buy a replacement diff which I obviously don't want to do?

Has anyone any ideas, itd be appreciated...