I'm frustrated

I bought a car in 2012 through west bank finance. They were supposed to deduct the last installment this month, R1700. They deducted the whole amount of R3700. I've been calling them since April 17 until yesterday. Every time I call lm being told that I will get back the money within 48 hours. Yesterday i was told that the money will be on my account before the end of the day. Up until today there's nothing