Bad service from Super Sonic and Comet projects

I singed up for Fibre to pay R645 per month. I am receiving invoice to pay R749 per month. I have made many calls to the Service provider and no one is able to assist. Even the company Comet projects who offered me the contract can't assist and the person Hayley is not making effort to assist with this. It's easy to send updated invoices and signed up the customer and later change pricing without making contact with customer. Please provide urgent response and resolve this matter as I am not paying any outstanding amounts for what I did not signed up for.