Xfinity Mobile, Can’t return defective phone!

I got a defective iPhone 17 where the side button wasn’t working. They gave me a replacement but said we’d need to add a new number or something. Now every time I ask for a shipping label they try to sell me some new internet plan or give me a new watch and I get told the label will be emailed in 5 days. I haven’t received anything and now my account shows 3 phones and a new number with a bill coming for over 250$. This is insane. I want to ship the defective phone back and have the new number removed from my account which should not be that hard to do.