Unnecessary conctacts just to trump up charges

Had an amount owing to Discovery which I agreed to pay , I paid regularly, and yet they continued contacting me at least 4 times a month?, the premise of thanking me for payment, or asking when next payment will be made etc etc, all were charged for. I had told the first person who called (at his offer of monthly contact) that it would not be necessary for them to contact me as I would make the payments as per our arrangement, and yet I got calls, sms's and emails continuously. I was recently gifted some money to pay off the account, the person who gave me the money asked that their lawyer glance through the account , he advised some charges should not have been made as he could see by dates of payments that there was no need for those contacts. He advised certain amounts be deducted from the final settlement, which we duly did and paid deducting a small amount of just over R300. We sent an email, listing the deductions and the reasons for the deductions, requesting that they give credit. I am now being continuously harassed R 521,16 at last contact and increasing with each contact ? Just a bunch of people making calls to trump up unnecessary charges. So tired of harassment now!