Vodacom issued me with broken IPHONE refusing to replace it according to policy

Vodacom issued me with a brand new Iphone11. The phone gave problems from the first hour. Crashing every few seconds. I handed it back within a day. After it was "repaired" it came back to me still broken. According to the Vodacom policy they should now replace the phone. They refused. Nathi Khosa identified himself as the manager. he disallowed me to cancel my contract or to get a new phone. The Vodacom policy counts for nothing and all I got was attitude. I do not want this phone back. I have now been without a phone for 2 weeks. I want this contract cancelled as I have only been in possession of this phone for less than 24 hours. Obvioisly my relationship with Vodacom means nothing to them as I have been a loyal customer for decades with multiple contracts running concurrently.