bad service, bad attitude and R40 k quote

I have been servicing my Land Rover at Menlyn Pretoria for the past 5 years. In the past 2 years I have complained repeatedly that the air con stops working after approximately 3 months and is making a noise leading me to believe there may be a leak. For 2 years I have been told the air con is being re-gased and all is in order however the problems comes back after a short time. Last week we booked our car for repairs and were quoted R20'000 which we accepted as we were led to believe the engine is about to seize and extensive computer diagnostics have uncovered several problems. On Monday we were quoted additional R20'000 to fix the air con. I immediately querier with the manager Rudi Pretorius and requested the full diagnostics sheet from all checks that were run since last week and a detailed explanation of repairs. He claimed he does not understand what I am asking for and ended up sending me an email with 1 line stating that because of the noise in the air con they advise that we replace the compressor at a cost of R20'000. Numerous calls and emails have led us nowhere. I believe we are being ********** and there is no solid foundation for the exorbitant quote of R40'000.