Not happy

I have a problem with MBD partnering with Woolworths for credit payments. I spend week calling and explaining my problem with them but no resolution. I was making monthly payment to settle my Woolies account and now that i am finished they are saying i still owe them and when i try to prove i am done with my payments they leave me hanging. Please help guys i am so stuck and I believe they want to continue debiting on my account. I spoke to a minimum of 3 agents and they all said they will call me back but nothing.