Bad customer services

I have an outstanding amount loan owes capitec bank then they handled my account to MBD CREDIT SOLUTIONS.all i receive is a basic treatment before the call agents were very nice they smsed me their banking details where i can pay,then i paid requested amount then when i ask for settlement letter they tell me that i have swapped the accounts i had 3 credit ,card,2 loans.i paid 2 separate accounts now they tell me that's money that i paid is for the other account but they are the one that send me account details.the agents now are rude, most of the teams when I call as soon as they notice its me they hang up even their supervisor is doing the same i got proof of payments with me all im asking for is to get a settlement letter or my refund and they return me to capitec