*****ulated and vodashop won't assist

I have a data contract of R59pm which is due for an upgrade and suddenly I get debited R709 near in mind I never did an upgrade, when I get to the vodashop kempton park, the supervisor tells me that an upgrade to an iPhone 6 plus was done on my name online and the phone was delivered and I never authorized any of this, the store tells me there's begging they can do for me but I need this resolved urgently and my money reversed