Can't Sign On The Site Keeps Telling Me That This # Is Already Associated With M

For the las t2 and 1/2 hours I'm trying to  post a new service on the site and i"m told repetedly that "this # is already associated woth my acct. My qoestutions is How shell I post and be able to verify by phone my acct. if that site continuesly tels me that it already knowa my # and it does not let me post???