Service fees for nothing

I had been an account holder of Edgar's for many years. I had always had my account up to date. I have paid up my account twice and yet there's always an amount owing.

I received an amount of +- R300 of which I had purchased nothing since settling my account. I enquired of what this amount is and the call centre agent says service fees. I requested a statement of how I owe that much and they don't state how the amount is 300 Rands but request that I pay before they hand me over to debt collectors.

Even when I went to check my account at stores they mostly offline, so how was I supposed to pay when it's their fault? Now they want to charge me double their service fee.

Do I have to pay this amount? I did not sign up for rcs service fees as I was with Edgar's before they sold their franchise. Do I have to pay this amount?