A program that grants points for using Bing search, which users can redeem for gift cards, sweepstakes entries, or charitable donations.
Since there are so many different threads about the same issue the logical thing would be to fix your form.
I sat on support with Microsoft for an hour, that rep seemed to think that you could select an alias to apply the phone number to and you can't. If that is a requirement to apply an alias to the new phone number just add a drop down or some means for the user to apply it. He kept having me go back over and send his screenshots. I would assume that all these errors should be recorded in your own logs for your dev team to review.
It very much seems, like with many companies, that support has no means to resolve the issue when it isn't user based BUT rather than acknowledge that and contact dev to fix the issue they just cycle back.
The rewards program not applying a phone number to an alias is not a user issue but a programming fail.
Sincerely, a former web developer. :)