Can only extend one time per entry. Then have to leave the country or do a border bounce. As of now people are not required to show anything on re entry.
For those in BKK who can't be bothered to jump through all these hoops or don't want to fly out. An agent called Nid at Visa Pattaya is offering a same day border run to Cambodia for 6500 baht. Probably will be quicker than trying to extend too.