CSR confirmed adding a line to my account would be free and one been getting billed for it anyway

On July 27 2025 I contracted a chat rep with questions about a BOGO mobile promotion. They confirmed that the promotion was live and that it would apply to my account. I also have a dated screen shot of the promotion from the 28th. 

i added a line but it has not been free.  Now support is claiming the promo expired June’s 25 2025 and won’t honor it despite the dated chat transcript and screen shot. 

How can I get this resolved?  Simple lying and saying the promo expired when I have proof it didn’t can’t be acceptable right?