Trade-in promotion and ECM not successful, hard to trust Xfinity Mobile

I had a trade-in device and got an amazing promotion ($830 value for an iPhone 17 Pro). Basically $30/month payments for 36 months and then $23 credited every month for the promotion.

Xfinity support has been awful. I connected the line on May 14 and then due to a mistake with the representative had to deactivate the line and re-activate it (transferring a number). Terrible support experience but now this is being brought up in every customer support conversation since: it was deactivated so the promo can not apply.

Then I go to a store and talk to manager and then via the in-store iPad escalation path get a full ECM ticket opened on May 23. Basically the trade-in vendor received the device on day 28 of the trade-in but took 3 days to process it (succesfully) so it was marked as 31 days and not eligible for the trade-in promotion.

Escalation confirmed these was Xfinity Mobile customer service mistakes, created the ECM, $23.05 credit per month, ticket was closed, saw it on the current statement, great!

But the next month, and this month the $23.05 promo is missing again. Contact support and get to run around in circles all over again. I was offered $23 one-time (instead of the $700+ remaining). Then tried to upsell me with a new promo instead of escalating! This is embarrassing. I loved the idea of Xfinity Mobile and Internet all in one but I fear putting any future phones or lines here.