Paying for a phone that I don't have

I bought a Samsung S10 phone on contract two weeks ago from the Sandton Vodacom store on the Saturday. On Sunday it worked, then Monday morning when I woke up the screen was frozen, the touch screen was not responding. Took it into the Vodacom store on Monday (two days after I bought it). They restarted the phone and then the screen was fine. But I refuse to accept a brand new phone that requires restarting to get it to work. So they sent it in for diagnostics (took 9 days). I got a call on Thursday to say that it didn't freeze during the time they had it and that there's nothing wrong with it and so now they won't replace it even though the phone was brand new...they also can't guarantee me that if it does freeze in the future I can bring it in for a new one because it falls out of the 7 days of warrantee. And they won't cancel my contract. So the phone is still at Vodacom. I am paying for new phone, but have no new phone. Please help!! This has been the most frustrating experience!