Ripping me off

I called in on the 8th Feb, requested settlement amount, I was told it's R4160, I called in again on the 16th Feb because I couldn't pay on the 8th and I was aware that the settlement amount might have been increased, I was told the very same amount. The following day I paid R4160. Today I'm getting an sms telling me I owe R74 for what? I call in, spoke to Melissa Oliver and she says we will listen to the recording but the one of the 8th? Why would you listen to the earliest recording and not the latest? That raised an eyebrow, how am I gonna be sure you are giving me accurate information? How can I trust your feedback if already you're telling me you gonna listen to the one made on the 8th? I payed the amount given to me on the 16th Feb. I am NOT gonna pay R74 that Homechoice decided to add only after settling the account. It's not my fault that your system add on amounts whenever if feels like.