My account debited 1000% more than agreed contract

I have a contract with vodacom for 20G day and 20G night for 299 per month. This morning, I saw a debit of R3000 from account , if this is not *****ing I don't know what to call it. It's even worse I cannot contact this people through e-mail everything is done through a call. The Galleria store where I signed the contract they are not helping but asking me to call accounts department . I need this issue resolved asap.