bad service

last year January I changed banking details and I did that with cell c so they have been debiting my fnb account since last year December. this year in march and april they didn't debit and I didn't notice that because I lost my phone but I made sure I left funds for them to debit. I only noticed that they are not debiting when I received a statement in may saying I owe them R1309.00. I query that via email and gave them a no that they can get me on, I spoke to an agent ,she told me they have Capitec on their system. who changed the bank details, no one knows. who is going to pay the arrears and the interest? cell c you are messing with my CREDIT RECORD you are costing me a lot. you are dragging my name thru the mud . I don't have that money so you will need to writt off those arrears as its NOT MY FAULT. I will never recommend you to anyone