Happen to me before at my friends father shop. I service change black oil only, then the worker tell me the aircond gas almost empty, ask me do I wanna refill it . I check the price then ok since I come few times d, can be trust gua. At first is ok, the next day not so cold d. Went back check, say might be leaking then refill again but still not working. straight tell me sitcoms spoil need to service cost me around rm1500. Of course I refuse. Feel cheated and not going back there anymore. Who know later ask me change engine also?  Finally fix at other place recommended by sister, atleast bettter abit even cost me a lot. 2 months later accident, hit a Merz, aircond spoil again. But thanks to insurance, I claim a new aircond. Even much cooler then previous one. Feel cheated again. No offense but I feel hard to find a trustworthy mechanic now a days..

lol i got mine done for 2.3k, replaced almost everything saved the cooling coil and the liquid pipes