cashback not payed since February 2015

I was promised a R10 000.00 cash back upon purchasing a car at Tata, which I did buy in January 2015 since then I've been sent from one sales man to the other and when I inquired in March 2015 was told ther were some documents are missing in my file and they promised to email the documents to me to sign of which it took them about a week to send me the said documents. I then signed and emailed back the document the same day and confirmed receipt with the sales man and he said everythings is correctly fieldand he promised that the cash will be in my account after 2 days of which that never happened and when I inquire after 2 weeks about the matter I was told that the documents iv signed it was incorrectly field and I should rectifiy the it and I did and I emailed it back and I was informed it will take 3 working days and now the date was on the 8th June 2015 on the 15th June 2015 I did sent an email asking about the progress and no response was given to. I so regret buying the car at Tata because of their bad service.