Disappointing Service

I had a done a retrenchment with jet I was told everything was paid off and the account is closed, now all of a sudden there is R105.00 which is owing and they have submitted my name to shabir debt collectors yet they have never left a message for me on their notes they say phone went to voicemail. I went the shop last year in september where I was quiring the R102.00 I was told that it was a mistake by both Stanley and the Manager now there is a R105.00 and another person says is due of me not paying the account properly which is do not understand as my account was never in arrears, I am fuming cause this damages ones credit score. I spoke to Catherine the Manger as the store I filled the claim with is closed and I have to now look for papers for them to deal with this query, "I fail to understand why a massage was not left. I am disappointed at the service i've received and don't understand why I should run around to ask people what was done and why all of a sudden i'm the one having to go around looking for people who dealt with my quiry.