Accumulation of installment after it was paid up

I was behind with my account instalments and was handed to lawyers but on 14/07/2015 I went to Maponya mall Edgars in Soweto to settle the account and cancel it. they took my money but seems the account was not cancelled cause when I checked with Edgars Ermelo yesterday the account had accumulated R500.00 charges from the lawyers. I just wonder how an account can keep on accumulating charges after it has been cancelled. is this the way edgars treats their customers? they even put me on hold for more than 30 minutes when I called in to enquire of the issue today, I used my hard earned money to buy the airtime I was calling with. I just want Edgars to sort this out because I am not paying the extra charges because I had already cancelled the account. they just have to figure out how to settle the lawyers charges without me, as it is not my problem anymore.