Trade In Complaint- Would Appreciate Any Help

Went to store 7/22 to upgrade during this latest iPhone promotion. The sales associate evaluated my trade in device  and based on model and condition (my phone was in perfect condition and to be safe i took photos and a video of the phone turning on just before going to the store) assured me i would get $600 in 24 monthly credits. He then said that they had no new iPhones in store and i would receive the iPhone at home in 2 days which I was fine with. When he tried to complete the transaction the system said “unable to process” so he asked the Store Manager who said that I would need to mail in the trade in and it could not be accepted in store as they could only accept it if they gave me a new iPhone. I reconfirmed a couple of times and they assured me i would get the full $600 for my trade in as it showed in the system and my phone was in very good condition. So they did the transaction in store but i had to mail in trade in device. At no point did they make me aware what the mail in process involved or i would just have gone to another store to complete the transaction. .

The new iPhone was shipped on 7/24 and I received it 7/26 and I also received the mail in label for USPS at 4.30 pm on 7/24. I mailed out my trade in immediately at 4.50 pm, 7/24 and have a USPS Delivery Confirmation of it being delivered to the York PA address on 7/26 at 12.49 pm. As of today my online account shows no update of the trade in being shipped or received by them and keeps saying to mail in within 21 days. I have received emails every 2 days including today asking me to mail in the trade in device. Also the billing online shows i have to pay full monthly price for the phone. Have called Xfinity Mobile four times so far and each time the agents told me that I am fully qualified for the promotion and that they can see it my account and I should ignore the emails asking me to send the trade in device and I would receive an email in 24 hours confirming the trade in credits. I requested them to make a note on my account of my USPS tracking number which confirms delivery.  So far I have received nothing but false promises from Xfinity Mobile. My buyers remorse window to return the new iPhone closes shortly. My window to mail back the trade in closes shortly after when I assume they will remove the trade in credit for my return. So I will be stuck with a phone at full price and have no access to get my trade in back. How difficult is it to have a system that scans the barcode as soon as the trade in device is received and updates the account that the phone was received. Also its only fair to complete the trade in process before the buyer’s remorse period of 14 days is over.

Sadly, at this point, with no concrete feedback, the mail in trade in program definitely feels like a scam and a restrictive way of making you buy a new phone at full price and stay locked in to Xfinity Mobile for another 2 years. In the process they are making me loose a perfectly good trade in device. Its just sad the wasted time and stress that I have had to undergo to get this sorted out and currently am no where close to seeing the end of the tunnel.  Any advise or help to sort out this issue would be much appreciated. I hope Xfinity Mobile gets back to me soon so i don’t have to take any drastic measures. I have been a Xfinity customer since I can remember at all my residences and a Xfinity Mobile customer since they started the service 6 years ago.