Vodacom refuses to help their clients

I have been a loyal customer to Vodacom for many years, until I experienced financial crisis and defaulted on my contract, I was still receiving statements and invoice from them on a monthly basis and the last statement I received reflected that I owe R506 of which I settled in August, when I call their Accounts department to get a settlement letter I'm told that I'm no longer their client and they can't view my payments or account details anymore because my account was handed over to MBD, to my understanding this is a collection agency but I should still be a Vodacom client, my ITC PROFILE doesn't reflect MBD but VODACOM, the lady I spoke to refused to help me and said I should call MBD, my question is, what happened to the payments I've been making to Vodacom? Where they just taking payments and not acknowledging them? I refuse to speak to MBD and want Vodacom to resolve this.