WOOLWORTHS ACCOUNT

My woolworths account was handed over to them, they collected R2000, I dont know what happened for woolworths to take the account and hand it over to Nimble, Nimble says I owe i told them I dont owe because MBD collected R2000, Nimble said i should ask MBD for a letter stating the amount they collected, i called MBD and i was told they cant help me because the account is no longer with them, all i need is confirmation that you collected the money so they can subtract it from my current balance.