Settlement Letter

I am very unhappy with Vodacom. I have been a loyal customer. In October I requested quotations to pay both my contracts off. I made the exact payments before end of October. I am now prepaid. Now in November the same debit order amount went off my account. I called and asked why because i paid exact amounts that was on the quotation and paid within 8 days, the gentleman explained it will be the last debit order still I do not understand why. I called Vodacom again requesting a settlement no one can help me I must do all the calling and no one cares. All I want is a Settlement Letter I will not not allow another debit order going off my account. The ref number I have is 1- ********** ********** . The reason why I paid my cellphones off is because of bad service.