Appalling Service from Telkom

I took the Unlimited Business Special (from Northgate Store) which includes telephone calls and data. The monthly contractual amount is R599. Upon picking up the phone, I was asked to pay a Deposit of R700 which I gladly did. To my surprise, I received an invoice totaling R2 161,35. I sent a dispute of this exorbitant invoice through the store and only received confirmation that R712 has been credited to my account. There is a line item to the value of R638.35 on my invoice which I disputed and no feedback has been provided.

My account number is *** and is a business account.