dispute over $200 savings on no trade-in required not being honored

Briefly, online pages says you get $200 off with no trade in when replacing a phone, it initially gives it to you but on the next page it takes it away if your line is a regular line (not premium as I now understand), but it doesnt tell you its doing that and it doesnt explain why the discount disappeared.

So my son got charged full price when he replaced his old iphone online from my account page- picked his phone line, chose replace device, picked iphone 17, and was given two buttons  - trade-in save extra $200 or save $200 no trade-in. He selected no trade, and it showed him a discounted price with $200 off over 36 months. Next page requires you to pick the line you are putting the new phone on (it only gives you one option, the line that you started to replace the phone from !) but when you select that line, it silently removes the $200 discount and shows full price at the bottom of the page, no warning, no explanation. He missed that and placed the order., and got charged full price. I later replaced another line with trade-in, and 1) it doesnt ask you to repick the line, and the $200 discount automatically goes through to the order page.

Deceptive even if unintended. Online call back agent told me you only get the discount without trade in on premium lines but it never told us that. His solution? return the new phone, hope they dont charge $35 restock, put number back on old phone, wait til return completes and then repurchase iphone 17 with trade-in (IF the offer is still avaialable then). I said that was not acceptable, then he told me to go to an Xfinity store and ask them for a $200  credit. I did, and they laughed at me, said we're a franchise and maybe try a coproprate store? I did and they again ran me round in circles, ending with the only option (my son has now gone back to college, I've got the old phone) is for me to go meet up with him, and go to another store to return the old phone - in the next 4 days we have left in the return window. apparently returning at the franchise store cant be done they say because he ordered online (even though he picked it up at that store) and he'd lose his number the minute they did the return. Corporate store might be able to save number. 

Reminded all of them that if this is their only solution, and we somehow manage to go through with it, Xfinity is now stuck with a USED iphone 17 on their hands. Not their problem their hands are tied they say. Customer service? Disservice more like. Hard to believe that this bait and switch web page design isnt intentional. Deceptive bait-and-switch. Hey Xfinity what can we do to please everyone? 

He didnt want to go through with a trade-in because of the hassle, and you only offered him $12. But he would have had he realised that was the only way to get the $200.

Now Xfinity says tough cookies, too bad youve already wasted 2 hours or more of your time, you bought it it's yours we cant do a trade in now, tough luck.

ChatGPT says file a complaint with FCC for bait-and-switch (and total lack of empathy but I get thats not a thing in corporate world).

Solution - Xfinity does a one-time account credit of the $200 they promised and then sneakily took away, and they AREN"T left holding a USED iphone 17 and we are all happy (as much as you can be with Xfinity). What they want - offer $200 to initiate replacement but then take it away  and have us to go away and pay full price.

Can we do this, Xfinity employee reading this?