Escalated Ticket [Edited]

We are a New customer as of 2.5 weeks ago and I'm pretty appalled with what I've been dealing with thus far. We are recent transplants from ATT and I've been working with a representative from sales named Joshua [Edited: "Personal Information"] -- he has helped transport 6 lines over. We purchased 5 new phones three S24 Ultra's and two Zfold 6's. I asked Joshua if xfinity mobile allowed us to exchange phones out to a different device within 2 weeks like other carriers did as we wanted to test out the zfold 6, he ensured me that that was possible. We received our new phones in the mail andported over our numbers. After using the zfold 6 I and my sister ended up loving it and my mom wanted to exchange her s24 ultra to one too. I called and ask for his assistance to do so -- he struggled to transfer the promotional deals we got one each phone ($500 credit and a total of $2500 for purchasing all five phones in a virtual credit card to pay off our phones from ATT). So he advised we go to a brick and motor store. We shuffled over twice with the employees there able to do nothing. So then I called him back and he and his supervisor said they'd help -- and they created a ticket with the back office bc something was up with the system. He advised me to keep the trade in devices until I received the zfold 6. 

The trade in devices were supposed to be mailed in by 9.20.24. And Joshua has been MIA for over a week and a half. I've been calling and calling and calling and leaving voicemails with no response back. I've called xfinity customer care and asked representatives to check on this ticket and someone just confirmed the ticket was closed with no resolution. There has been zero communication as Joshua said the back office would be reaching out to me. I've called xfinity every single day for hours and hours for a resolution and help. And no one calls be back or I'm left to a dead end with the care team saying this is too complicated for them to resolve. 

I'm not sure how to return my trade in devices anymore as I'm afraid they'll get lost and my promotional credits as promised wont be given to us.