Upgrade dispute the contract amount confirmed changed after the product delivered

Disappointed in the service of vodacom. You upgrade receive the product, then after TWO weeks of using the product , you get sms off a higher new contract prices and new “order”, you call you query… and the only resolution offered is to fetch the phone and cancel your original now amended upgrade … only saying “sorry” it was a system error, and the original agreed upgrade confirmed price was not correct. And not even responding to emu of the emails query sent. Poor at the very least of dealing with the “error” on the company’s side. I know that if buy a product I pay the price that was advertised,.. be warned.