SHORT PAYMENT ON TRADE IN AMOUNT

My issue involve staff members ( Kenneth & Martin) <br> On the 20th of March 2015 I bought a 2015 Toyota prestige and traded in my 2009 Toyota corolla professional. After the trade in I was supposed to receive R18 164, 00 but I was paid R15 000, 00 on the 14th of April 2015. A follow up was done by myself same day trying to find out what could be the problem Kenneth (salesman) acknowledge that it was omitted by mistake and it will be attended to immediately. I kept following up the matter until the end of April where Kenneth advise that when the branch is paying all creditors I will be paid end of April as well. 30th of April went by still no payment, numerous calls were made to him where he kept promising till to date no money paid in my account. On the 16th May I called Kenneth he advised me to call Martin, Martin was called by myself where he told me he is going to call Kenneth since he was not in the office but he never returned my call. On Saturday 16th of May 2015 at 09:26 I then called Martin to find out why he did not return my call after talking to Kenneth on Friday, he then indicated he have cash he will deposit to my account same day or Monday 18th, to date no payment help