Refund problem

I app**** for a home internet online a few weeks ago. The lady gave me a wrong reference number to pay for my prorata fees. Ever since then mtn has been playing games with me. Nobody is willing to assist in order for me to get the refund. I've been calling and emailing them nonstop and im just going fighting a loosing batle. The latest response i got from enail is that apparently the payment i made was to a non mtn nanking account,but the account is the same as the one they have published online. I dont know what to do now