Unfair,rude and dont care about their customers

My account was in arrears ,so i decided to settle the account and communicated with foshini OF my intension and i was advised to pay into their account ,26 october 2018 i paid my installment to their accounts , suddenly when i request balance TFG they couldnt help and tells me they cannot updates my payment untill full balance is paid and tells me that my account has handed over to MBD on the 12 Novemver 2018 with added about 40% interest . My account have ballooned to more than 50% of the debt owed but my statement online and credit bureau shows the different.I requested for the details of interest rates but no one from both foshini Neither MBD can show me their calculation of their interest.