Poor Service - Refund still outstanding

Bought a vehicle from them during the month of November 2018. Their Customer service is pathetic. I have so much of problems getting things sorted out. I am still waiting on a refund to be paid to me since 8th December 2018. I have had dealings witb my sales lady, sales manager as well as the Dealer Principle. But still have had no joy. I would NEVER recommend that dealership to any of my friends. They give my car back to me with an empty tank after I gave it to them with just under half filled... I was on the verge of cancelling my contract with the bank to return the vehicle. All my communication I have on email with them. How long can a refund of R591.00 take?