I have bad experiences getting ripped off from service people, but its bloody hot and my A/C doesn't cool down my bedroom when its on full blast in the slightest. I have just had a freon topup fairly recently, who are good people to contact to service/clean it ?

I wouldn't know how much one professional charges. I've only dealt with teams of 2-4 dimwits, who charge 300-400. Sounds like you have leak(s). Running it on high will only give you a massive electric bill and put lots of wear on your compressor.

PT Air Service as mentioned by me in other threads will fix a/c problems. Usually a power clean of compressor and condenser will restore full cooling output but they will also check refrigerant pressures and top up if necessary. 2 years of accumulated dust, regardless of scrupulous primary filter cleaning, is all it takes to reduce a/c efficiency by 50% or more.

PT Air operate from San Patong, south side of CM.

PT Air Service as mentioned by me in other threads will fix a/c problems. Usually a power clean of compressor and condenser will restore full cooling output but they will also check refrigerant pressures and top up if necessary. 2 years of accumulated dust, regardless of scrupulous primary filter cleaning, is all it takes to reduce a/c efficiency by 50% or more.

PT Air operate from San Patong, south side of CM.

I just had 3 A/Cs cleaned, all for the first time after more than 5 years of heavy use. They were filthy. Now they look and work like almost new, it is really a shame I didn't know they offered this service before it would have saved me 20k baht for the new Panasonic I just bought. From now on I will have them cleaned every couple of years. They also checked the refrigerant, happily none needed. It only cost 350 baht each. Great deal.... would have been worth 500 baht each in hindsight.

Won't help to give name/number of the guys cause they work in Phitsanulok where I live. The guys do A/C installs for Thai Mart, Big C, Lotus, Home Pro etc. but they do the cleaning on their own time. Call the CM Co. listed in the above post by kaptainrob or call Thai Mart and ask for their installers number... should put you on the right track. I'm guessing you won't be sorry if it's anything like P-lok.