On my experiences, I would like to suggest you to go with ksrtc online booking. Take a deep breath, book the tickets leisurely. You will get the best class service from ksrtc for sure. I have been travelling in airavath volvo for quite long time.
I havent been cheated or mis-treated by the service.they maintain proper timing. Also, the recent introduction of corona ac sleeper is very good.the interiors of the buses are very excellent. Also, the blankets they provide as very neat and clean.. You feel as if you are sleeping at your home. Really excellent service i have ever seen. Earlier i used to travel through kpn sleeper service. But now, since ksrtc has introduced the sleeper, i feel quite comfortable and even the interiors and comfort level is far far good than kpn services.
Guys, dont get cheated of many stupid travel agencies. Go with ksrtc