Wrong phone delivered

Firstly please fix your website. When you’re advertising a promotion why not deliver what is promised on the promotion? The Samsung S23 Ultra you get double the storage for free so why is there only one option to choose from being the 256gb? There shouldn’t even be a choice it should be 512gb and that’s it. Now I got the 256gb delivered last week Friday, have been making calls after calls after calls for someone to collect the phone and to cancel my upgrade as I no longer want it. I’ve been put off cell c completely and I use to love cell c and never had any issues up until now. You can never speak to a superior and you have to explain the story to someone new every time you phone so unfortunately this is my last resort hoping I’ll get somewhere. I will not accept anything less then a cancellation of this upgrade in writing confirming this and I will not be held responsible for not having canceled in time because I have and legally I have full right to do so. Please somebody help me resolve this issue.