Need help: ATT does not want to give me sign-on rewards

Hey ATT users. 

Need advice on what to do. 

I've signed for home fiber internet last November (2021). ATT had two promos going on and claimed I will get two reward cards: $200 and $150, which was the primary reason for me to try switch to ATT from XFinity.

Unfortunately I did not receive neither the cards nor any info about my rewards.

I did contact ATT support and ATT rewards center several times both in online chat and via phone starting in January. The responses were "just wait and you will get it" in January and February. On March 7th I was ping-ponged several times between rewards support and regular support. They have done something internally, escalated something and claimed I will get the reward cards soon. Well nothing in the mailbox for another month. Today is April 4th and I have called ATT Reward center once again. However now they say 120 days have passed and they cannot do anything.

Any advices on what to do next? I really like ATT internet, but I have had a really bad experience with customer support and kind of stuck with where to go next and how file my complaint.