Cheap Rates ,Poor Service

On the 30th of April i received a call from a Capitec Consaltant to make payment arrangements on a loan i have with them and arrangement was they would deduct R1000.00 on the 11th of May which they did. On the 14th of May a consultant from the collection Dept called me to inform that they had received the money and further more arrangements to be made in order to continue paying a loan i owe to them ,agreement was made that i'd continue paying forth nightly installments hence on the 15th of May i received a notification that Capitec has taken R1588.60 from my account and that was not the agreement i called them to inquire and ask them to reverse the money and i was being transferred from one dept to another without receiving help .When i finally got someone that was willing to assist they only reversed R730.16,this makes me worry as to how safe is one's money is?When they have a loan with Capitec and especially if one is to receive their salary from this bank would they just take what is owed to them & not what was agreed upon without the clients knowledge?