Not very helpful. Unnecessary charges

So before my account fell into arrears I called Foschini monthly to get my installment reduced, they kept on telling me that my account was up to date, wasn't able to assist. The reason why I made a bit of a lump sum payment was because I stopped working in November, and I only started working in July this year, but the salary that I am earning is far less than what I was earning previously and this is what I probably told 2 or 3 people once they started calling me when my account fell into arrears. I made an arrangement that I could not keep to. This month I made a payment 900+100, now after the arrangement was broken and after speaking to someone I have been receiving called from them for the past week since last week, they called me twice yesterday and I told them that I'll report them if they don't stop. I checked my account statement and it shows that I get charged R20 per call, even no contact was made! This is pathetic because I am trying to get my account up to date. But how if I get charged for things like this??? And like I mentioned I have been unemployed since November 2019 up until July 2020. This is the first time my account has been in arrears after how many years. This unnecessary nonsense must really stop, this R20 phone call charges is also ridiculous. PS:Also just to add onto this, the last 2 ladies whom I spoke to was very help and understanding, THANK YOU