Bad service

I went to upgrade my cellphone contract and was offered a contract with OPPO and now I cannot receive incoming calls. I have been back to Mooirivier Mall in Potchefstroom to ask for assistance with no luck. I have phoned customer care for help, with no change. I am executing my consumer wright and returning this device tomorrow morning and cancelling my contract. I have spend a day at the shop and about 3 hours on the phone with NO RESULTS!!!