Contract upgrade gone wrong!!!!

I upgraded to a Samsung S20 and I was told that I have 7 days to return the phone if I don't like it. I asked for the S20 to be collected from me since I don't like it. All I wanted was an S20+ on a Pinnacle 2GiG top up package that comes with a Samsung Watch But I was told that since I opened the box of the phone, they cannot collect it. CELL C I AM NOT HAPPY WITH YOUR SERVICE AT ALL AND I DONT WANT THIS PHONE