I used a car service last week from BKK hotel to Pattaya and return.The company is located in Pattaya and is called MrT. The cost was 1000 baht each way tolls included. the 2 different drivers knew exactly where to go and
avoided some construction on the way down. The cars were a Camary and A toyota mini van. The best car service I have ever used for the trip and would recommend them highly. Oh this is a 24 hour service I asked to leave Pattaya at 4am and the friver was there on time.
I am sorry I do not have the phone number at this time I will locate it and post later or PM me for the info.