Not able to add a line to my account.

I’ve tried multiple times to add lines to my account through different browser and the app and haven’t been able to add a line. I’ve ended up having to do it through twitter where they genioursley have waved the $30 fee since the site wasn’t working. I just want to know why I wouldn’t be able to do this on the site since going through Twitter requires a lot more time that I don’t really have.

Thanks!