Can't access voicemail

I just attempted to retrieve messages for the first time.  I entered *99, got the system which told me I had 8 messages.  It said to play messages enter "1" which I did.  It did not recognize any entry and continued offered options until it had me enter the phone number associated with the account.  I entered my full phone number and it replied ""40507" is not a valid mailbox number.  I haven't been able to access my work voicemail since last Thursday and this really doesn't look good for my business.  Help!