Im being ******

I owed Truworths and my account was handled over to MBD Legal collections. A lady foned me and sent me a statement. The amount on the statement was R2600 and we made an arrangement of R400 i paid R400 the first time skipped one month and paid R800 and lastly i paid R1600. I then sent an email requesting a settlement letter and they did not reply until last week where I received an sms which said I owe them R301 and a call again last night where I was told it's now R390. Clearly they add interest every week, why did they wait until now to contact me for this debt why ddnt they call me for this money immefiately after the instalments i made. I paid almost R200 extra how do they calculate these interests?<br> <br> I am really angry it feels like they dont want me to settle this account. They didnt respond to my settlement on purpose so that they can continue putting me in debt. I demand justice on this matter if there was anything left that i need to pay it must be based on what was due when i asked for a settlement not the R400 they asking for because i can see that next week it will be R500.