Worse retail ever

So I have an account with them and I was in arrears when I was on maternity leave but I made sure I pay extra when I returned to work and now every month they give me a call to ask me when am I making payment to make matters worse they charge me R20 for these calls and they charge for sms' I never asked for it all goes to my account how will it be up to date if they continue calling and charging my account for calling me. Now my account is blocked because they want me to pay a certain amount that I can't afford I make sure thay without a doubt I pay R500 into the account yet they forever sending me messages telling me my account is in arrears it wouldn't be if they did not keep on adding unnecessary sms' and calls to my account they very unprofessional nxa