@Nimz77 I havent been to Platinum Auto Spa yet, but I personally know one of the guys who runs it. A petrol head and has a good knowledge of vehicles and takes pride in his work. Can't comment on the pricing but I'm sure he maintains his quality.
Another place you could try is this garage at the top of Hill Street Dehiwala. When going up from Galle road you will find it on the right near the split in the road. They specialize in quick paint jobs, cant remember the name though. Took a Nissan Bluebird CVT there and they did a decent job and matched the paint very well.