It seems you have some bad experience with bus transport in Thailand. I personally use a lot of bus transport in Thailand, and I think a lot of the services are decent if you find the right one. The best way is to book a ticket online. It saves me a ton of time to find the right transport provider compared to finding it locally at the station. Several months ago, I had a chance to visit Phuket and book a bus ticket via an online website, and this website has a lot of buses available to choose from. I did pick a transport company, and their services are pretty good, so you might want to check this website out www.busticket.in.th when you have a chance to visit the south of Thailand again.