Right... I'm back home and thought I'd give a little update
I took your advice and spoke directly with the mechanic, asking him which part cracked and how that happened.
Turns out it was poorly communicated to me in the first instance by the receptionist, so the mechanic said that he went to put fresh refrigerant gas into the system and it came straight back out i.e. there was an existing leak/crack in the compressor therefore he was unable to carry out the air con service
Not that I can confirm as I don't know for sure, but maybe this would stack up with it working so consistently bad since I've owned the car (just over a year)
At least I know exactly what the issue is now and how to sort it!
He also found a few other bits that need doing
- Both rear shocks are slightly leaking oil
- N/S/L Strut has a slight oil leak
- Both front lower arm rear bushes split and cracked
- N/S/F Drop link dust cover split
- Advise on front brake disc's being slightly lipped on the inner edge
- Advise on front brake pad's being approx 3mm of friction material
- Advise on rear brake disc's being corroded and slightly lipped on the inner edge
- Recommend brake fluid change due to having moisture content of 4% or more
Quite a list considering I thought the car felt fine, particularly the brakes and pretty confident I had a brake fluid change 6 months ago in my major service. The mechanic did say though that none of the above is urgent and just needs looking at some point in the near future..