Overcharged on contract for out of bundle data - can I speak to somebody?

I've been with MTN for over 20 years with the odd issue. However, in May I didn't receive and email account, and the debit order went off, which was fine. In June, I received an invoice and was charged my usual fee PLUS R1775 for 5GB of data. After numerous calls and holding for up to 30 mins at a time, I was told it was an out of bundle rate charge. Even the Call centre said it's strange. (1) The amount charged was above my set limit and (2) out of bundle or not, R1775 for 5Gb of data is crazy, I've sent an email to the Complaints email address, but can somebody please call me to explain.