Handed over while paying

I had a loan with Old mutual finance.. Years passed I couldn't pay the loan they garnished it.. So it was now going through persal.. Earlier this year I noticed that Old mutual finance is now longer in my credit profile but was still deducting , as I was still trying to understand that I started receiving call from Nimbe group stating that my Old mutual account was handed over to them.. I explained to them that this account is deducting a certain amount in persal.. A day doesn't pass without them calling demanding that I pay them because now Old mutual takea more time to give them the money deducted from me.. Kindly assist on this matter as I am now having Nimble group im credit profile demanding the payment.. also how possible it for the account being handed over while It's paid every 15th of the month.. I have tried calling and explaining to both parties.. Old mutual say I must contact their legal team.. I did now their legal team says they can't go through my account because it has been sold.. when I call Nimble they send to Old mutual.. I am just a headless chicken calling all the time .. Honestly I cant pay bot parties.. Old mutual finance refuses to cancel the garnishee so as to be able to Negotiate with this group.. Kindly assist