How come BOGO plan was not applied to my account after I switched to Xfinity mobile

Hello, Xfinity support expert.

When I renewed my internet plan, the agent persuaded me to switch to Xfinity mobile, too. 

She mentioned BOGO promotion to me multiple times over phone calls and I saw the BOGO(buy one line and get one line free) promotion in the Xfinity mobile website, too.

However, the first month bill was not applied with BOGO so I called and chatted for +15 hours to resolve the issue but got 2nd month bill without BOGO plan again. 

During another 3 hour call, the agent created a ticket [Edited: "Personal Information"]of  and told me it would take 10 days and promised to call me. Nothing happened and got 3rd month bill with the same issue. And I asked this forum with the ticket# and some one said the case is closed and asked me call or chat again. 

I need to understand why BOGO is not applied after I switched all three lines to Xfinity? Definitely BOGO was a good reason for me to switch to Xfinity mobile after using ATT for 15 years. After I switched to Xfinity, no promotion and no word from Xfinity is given to new customer. 

Please help, thanks.