Agreement broken

Last month I was due for an upgrade which I took. I took this contract out for my 14yo daughter in case of emergency. When I initially entered into the contract I phoned vodacom to cap any and all out-of-bundle usage as I had no intention of paying more than the contract amount, which vodacom did. The upgrade was for R249 per month. I just received an account for R1 620.09 with another R1 300 due next month. At no time when upgrading did vodacom let me know that my standing order of capping any and all out-of-bundle usage would no longer be valid. This is unacceptable and plane ******ion. I phoned vodacom to complain, was first given the run around and then told that my complaint was escalated but would only be contacted within 16 working days due to large volume of calls (large volume of dissatisfied customers, I'd say).