Who I have the same questioned this topic

1/12/21: Saw $440 trade-in promotion on two of our Start unlimited lines. Both had Galaxy Note 9s. Purchased a Silver 12 Pro Max for one, trading in the old Note 9 for $440. Got through the whole process, signing all documents, even received an email receipt stating all details: phone purchase, current line, trade-in value. No mention that the plan needed to be a "premium" line. Besides the promo would/should not have worked in that case on a "start" unlimited line which is a basic unlimited plan. We did this close to midnight so when we tried it for the second line, it was the 13th and the promotion was gone. I figured it must have ended on the 12th and we were lucky enough to get one done.

1/15/21: Fast forward a few days and no indication of phone being ready for pickup. These online pickup orders are usually ready in 24 hours so I called the store where I was going to pick up the phone and they tell me order probably has been cancelled as there are inventory inconsistencies. Verizon online orders think authorized retailers have phones in stock when in reality those phones have already been sold to other customers. Rep in store explains they have to add it to inventory even when phone is already sold to a previous customer and Verizon online thinks it's an unsold phone in stock. I get to the store and sure enough, that phone was for a different customer and my order needs to be cancelled. Luckily they have a different color 12 pro max that my Father in Law wanted so we decide to upgrade the device for that line. All along my concern is for the $440 trade in promotion that needs to be redone on this line since the original order/trade-in needed to be cancelled. The in store rep assures me they can transfer all promotions along and the credits should be the same. If anything they can do a promotion correction through a form. We wait an hour on hold for this whole cancellation process to be done as Verizon customer service is confused why the order needs to be cancelled.

1/16/21: Sister in law mails in Father in law's old Note 9.

1/17/21: I receive cancelled trade-in return packaging, again it reiterates the trade-in value should be $440.

1/25/21: Received an e-mail saying trade-in value was corrected from $440 to $138. Reason citied: Better qualifying promotion found.

I've been on the line with customer service a few times now and it looks like the promotion has always been for "premium" unlimited lines and it was a glitch that let me get through with the full $440. The reps say they can't do a proper promotion correction back to the $440 unless we upgrade that line to a premium line which will cost us at minimum an extra $10 for 24 months = $240 (+taxes and fees). Otherwise the trade-in value will stay at $138.

Currently waiting on a call back from a supervisor but according to the previous rep their hands are tied as well. Will try to negotiate some bill credits for the rest of that $300 but it looks like my chances are slim to none at this point.

Seems pretty unfair I get shafted out of $300 because a glitch in their system let me through that promo.

Tl;dr: $440 promo let me trade in a phone on a basic unlimited line for $440 but reps say it was a glitch in their system and refuse to honor trade in value for $440 but I will get a measly $138.