Has anyone had luck redeeming promised rewards after 120 days?

I signed up for ATT internet with what seemed like a good rewards offer... not realizing I had to set my life and calendar around holding them to their word I totally forgot to follow up about it. I received no rewards claim number or anything further about it.

Today I started the arduous task of tracking the reward down eventually to find a reward number to call only to be told I can't have my reward because I only had until September 2022 to redeem it. I was then passed on to a loyalty department who seemed baffled that I was calling them as "It's nothing to do with them"

I have the original online chat where I was made the sign up offer. 

Has anyone had any luck in this kind of situation? 

Is there an email I can forward the online chat to to have someone higher-up look into?

I'm pretty (Edited per community guidelines) about the whole thing so at this rate I think I'll just have to cancel the service and try and find a more honorable/organized provider :-(