Question : Sonicwal change IP

Hello there -
Office moved to another location.  ATT saying we need to change the IP in Sonicwall to reflect the new gateway. I asked to bypass.  They tried but no aval.  Users cannot access Internet.  
So few questions:
 - Is there a way to access the sonicwall if no one knows the password?
 - why cannot bypass the sonicwall?
- do I need to know just a gateway to change the config inside there?

Thanks in advance

Answer : Sonicwal change IP

Yes the SonicWall give you one free VPN client connection.  You can download it from the mysonicwall.com site.  You might have to contact SonicWall if you do not have the device registered under your name.

After the 1st VPN client, the additional are at a cost of abou $50USD