I can't access my mother's account, even though I'm getting billed, and I can't reach support.

Thanks for posting this on our forum, Rocklobster. I’m really sorry to hear about your parents.

I can totally understand where you’re coming from, so let’s have a look together and see what we can do.

From what you mention, it sounds like you’re being asked for this one-time code to access the account in question. 

Are there any other devices that could be still logged in to the account? If yes, please check their notifications; the one-time code can sometimes be found there.

If this doesn’t work for you though, we can log a ticket and look into this further.

Finally, when updating your billing info, you did this directly on the Dropbox website and not iTunes/Google Play, right?

Let me know, and we'll take it from there.