Old age is the likely reason for its demise.
My mechanic hasn’t mentioned another suitable replacement part and he would know. The £93 one is probably the best option. Fitting etc will be around £100 including regas- the air con place will fit it not the mechanic.
I need a new air con compressor - genuine new Audi part £1600. Used genuine Audi part £93 posted (with one month warranty). Do I even need to ask?