Costly Mistaken Debit order

A few months back SSDA took over my account with discovery . 2 debit orders went through , I reversed one as the agreement was for 1 , a few days later I got a call from one of their agents stating that they have not received even 1 payment.

After sending proof ( my banking statement ) the agent said that he has spoken to their finance department and that my money (DO) was allocated mistakenly in some ones account .

I have called them numerous times and I was told they are still on the case ,its been 3 months now and no money has been allocated to my account to decrease the amount I owe.

Meaning the other clients account has decreased with 1100 which I paid and which they mistakenly allocated .

It is frustrating because every time I call no one gives me a proper response and when I speak to the agent he states that its still been handled .

All I want is for my money to be allocated to my discovery account to decrease what I owe so I can pay off my medical aid account ,but the inconsistency ,expensive mistake and the lies that I got from the agents it heart breaking . This is my last desperate resort for SSDA to fix this mistake . Can I speak to some one who knows his/her business and who can fix this ,clearly everyone I have spoken to has no ability to help me .

Is it hard to move money from one account to another , I mean the company deals with Credit/debit/money on adaily basis :-(