I booked the 2 pm van back to BKK ; asked if earlier travel available ; was put on the 1.30 pm bus - had comfortable ride into BKK ; the driver was very helpful with luggage in and out of the bus - I bought a luggage seat ; note to fellow travellers - from Pak Chong Mr " Pylon " at 086 721 5011 can provide good support for your ride to your hotel & whole day criss-crossing & stopping wherever you want in Khao Yai National Park 8am - 6pm for a reasonable price. Check him out - tell him Lee & his son from Malaysia recommended him.
My seat was broken and I couldn't lean back. The minivan was packed with people and didn't provide enough legroom for a tall European like myself. We left and arrived on time.