Double deduction

I took a loan with with fin choice of R4000 November , I was told my 1st instalment is going to be on the 22nd of December 2017, to my surprise they debited on the 5th of December and obviously there was no money into my account and I got charges R49 every time they try to debit my account . Come the 22nd December they debited 3 instalment of R983.85 I phone for a refund of R1966.70, They only refunded R983.85 , I phone in and I was put on hold for more than 20 minutes and they promised that a superviser will get back at till now , I had to phone them again I was put on hold another 20 minutes the consultants said Team leader will call me back, I am still waiting for my refund I told them I will speak to my bank and reverse my money , I am never doing business with them anymore