Looking for non-dealer auto maintenance/repair shop in Bangkok

Can someone recommend a non-dealer auto maintenance/repair shop in Bangkok for my almost 20 yrs old Toyota Fortuner please?  

My 19 years old Fortuner's optitron meter no longer illuminates (it does but often takes time, sometimes not until 15 min after ignition).  I brought it to the nearest Toyota dealer but all they can do is replace the whole instruments panel which costs almost 15,000 Baht.  I've done some Googling and it appears there are easy fixes that involves changing IC/condensor behind instrument panel and it doesn't even cost 1,000 Baht.  But it's a skill beyond my ability.  I can spend 15,000 but I guess I don't want to spend that much for a car that's probably not even worth 200,000 Baht.  I can find a lot of body shops but not maintenance/repair shops around where I live in Sathorn district of Bangkok.  Any idea where to bring my car for an easy but affordable fix?