Promised $400 gift card per line in writing , received $200 per line, agent not responding.

As was reported similarly by another couple users.... In Feb 2025 I switched 4 lines from other carrier to Xfinity Mobile, and was promised in writing by comcast business account representative rebate of $400 per line, and no contract with month to month service plus a discount on my business internet.

Its  Jan 2026. and I just now received 4 Visa Gift cards for $200 each which is $800 in total short.

I had a business agent, who offered me this deal, I have his name in email correspondences regarding this if necessary. After selling me on this deal, he promised to call me back and follow up about the missing gift cards, then he stopped calling,  stopped emailing, his last response was that he will look into the issue, then he just stopped answering calls or following up. 

I am not sure if Comcast/ Xfinity will fix the error or if I need to contact a lawyer, BBB and FCC and other to help.