Poor service

I am currently unemployed and requested them to cancel the monthly debit order as my account is overdrawn and the payment is going to be returned. I will make electronic payments when I have money. I was told that according to my contract a debit order needs to be in place. They debited my account on the 31st and I made a manaul payment on the 1st. The payment was returned by the bank (I told Cell C there is no funds in my account) and then Cell C audacity to charge me R70 for late payment fee. I have been a client for at least 14 years amd this is the treatment I get. Why can Vodacom cancel a debit order and accept manual payments? You also pay much more for less with Cell C. My account is a mere R280 p.m and I get 100 min, 100 sms and 100mb. My wife pays R600 with Vodacom and gets 600 min and 3GB, Cell C is a freaken *******. Guess where I am going when my contract expires, not Cell C.