Bad service

Just few weeks ago I was happy with the contact phone I got from Vodacom. I call them yesterday to change my payment date and just after the call was ended i got text saying I own R918.00. I called them back to find out what is this amount for. I was told Vodacom requested contact money on the 29th July and they didn't find the money and that means for July I didn't pay my contact. On my bank statement and App I have proof that R430* 2 and R120.00 was taken by Vodacom on the 29th July. If this is not going to be sorted by tomorrow I will cancel the contact I promise and I will involve my lawyer. Is not over three months from this contact but I am having issues. This is bull. Vodacom don't make me made. please