the worse customer service ever

this is the worse customer service i have ever seen , they failed to debit my account for two months no communication or whatsoever. i went and paid the money straight at the bank , now i need a simple letter stating that i have paid the amount and my account is in good standing am told i can not get such a letter, this is pathetic, as soon as my contract expires in August am gone never coming back shemmmmmmm. *** Cell C Customer Service Case Number : ***