UPDATED: i spoke to two customer support people- after asking me literally 5 different verification questions, the first person claimed he couldn't even find me in the system. i hung up, redialed and got someone who was helpful.
he confirmed that my current phone number is already attached to a different airbnb profile that is in no way related to mine. he told me he was going to escalate to someone who handles this type of issue and that the issue will be flagged in general.
so, as of now there's nothing i can do to update my profile, but allegedly i will hear from someone who can hopefully help me get this sorted out. in the meantime, email is the only way i will receive updates to any of my reservations.
i'm having the same problem. only have one airbnb account. lost old cellphone. had to get a new number. went to update my profile and it won't let me add my new number- "This phone number is already in use. You can remove it from the associated account or add a different one." won't let me delete the number i no longer have. this is really, really annoying.