I cannot use my registered account!

I just registered my Xfinity account with my email and American phone, but I found that I cannot purchase my product. It needs my birthday and it failed to identify after I typed my birthday.

I also clicked my "account and identity" but it just showed "Something unexpected happened." 

How can I connect to the support team because I can't ask a real agent, the robot kept asking to log into my account but it always failed!