ATT internet fiber promotion

Placed a new order for internet fiber 300 .. They are/were offering $150 promotional rewards prepaid card + I had a promo code (+ $50) + the rep offered an $50 for placing the order now via the phone. In total, $250 promotion.

The confirmation email only showed $150. I called new service hotline, on the same day, they said the $100 wont show and that is handled manually. 

2.5 weeks later, and before I started the service, I called again to confirm. I got routed to tech support - who confirmed only $150. Asked to be transferred to sales - confirmed the same $150, and said if there is a $100, they cant see that right now and only would see that after the $150 is claimed. 

I spoke to another rep, who said the $100 is manually handled, that they don’t have a way to track it right now, that they cant send me separate confirmation email nor is there a confirmation #. That the notes are being tracked and call back again.

I bet they are hoping you forget about the $100, and by then it doesn’t matter as the service has already started. This is a reminder to chase yours. 

Also, isn't this borderline predatory selling, offering perhaps fictious promotions the company isn't even aware of. I feel bad for the  poor guys/gals in CS who have to deal with their sales counterparts offering BS, to clean up after them.

What would you do if they don’t honor $100?

PS: Mind you, an off shore sales agent said 300 is not available and that I would have to go with something higher. HAHAHHAAH - clearly wanting to upsell. That's when I had to ask for an onshore sales team member.