MailChimp Question

I have been using MailChimp for free for a few years now and have a list with scores of email addresses on it I use every few months. Last month my cell phone number changed and now it tries to send a two-factor authentication code to my old cell phone number and fails. I need to have the number updated, but there is no way to contact support without purchasing a plan which as a non-profit I am loath to do. So I am stuck. No way to contact MailChimp to change the phone number, and no way to actually get in and use product. Before I give up completely are there any ideas to get around this? Two-factor authentication is great, but only if you can update your phone number if it changes…

Sign up anew with your new cell phone number?