The two device limit does create some challenge in managing devices. The key is, I think, to always sign out of a device and then remove it from your account before then accessing your account from an alternative device. Remember, too, that you can only unsync twice a month.
Since the web access is needed to manage your account I would have signed out from the mobile device rather than the web.
The only quick solution would be for you pay for a one month subscription then cancel it after two weeks and before the renewal for the following month comes around. That will give you a month to resolve the issues. Otherwise, wait until the 30 days is up.