My account debited twice

I have a loan with DirectAxis. When it was in areas, i was called to make arrangements to pay areas. 4 months ago, i agreed to pay R500 extra towards the areas including full instalment. The arrangement was that, the consultant will call every month after payment so that he can make further arrangements for the following month. For the past months the consultant was not calling. I received an email dated 23 September whereby I was informed that i made an arrangement on 23 September for a deduction of R500 on my arrears. No one has called me, no such arrangement was made as i have paid up all my arrears. What was supposed to be debited on my account was only tge instalment. I need to be refunded my R500 immediately.