PAID UP LETTER

I opened a Jet account and stopped paying because I was unemployed, so they took my account to Norman Bissett & Associates. When they called me for not settling my account I explained to them that I am unemployed. They asked when am I going to settle my account and I told them that I still need to talk to my family member to help me. So we made arrangements for me to get it settled, there was a time when i could not pay again because my aunt had financial problems. Then I got messages telling me i need to pay before the take legal actions and I started paying when i got the money. Then there was a time I talked to them and they said I owe R600 and something, I paid maybe about R400 if not R600 to their account but they kept telling me that the money does not show on their system. When i asked them how?they told me it takes 7 days to appear, I even sent them the invoices to show that i did pay but still they kept on saying i did not pay. So I am wondering where did that money go and the invoices i sent to them?They told me i should pay at the store because of this sittuation so did exactly but I still owe them...PLEASE HELP i do not know what to do anymore.