Which Slingbox are you connecting to that the channels do not allow you to go past 100?
After a look on your account, it looks like you have a Slingbox SOLO and a Classic.
If you are connecting with the Slingbox SOLO, I would recommend to reconfigure the Slingbox and select the Digital option of your TV service.
If you are connecting with the Classic, being that the Classic only connected via Coaxial connection, if the signal coming from your cable provider is scrambled, the Slingbox may not see the higher channels due to the box is only analog.
Please let me know if reconfiguring the Solo helps!!
Sling Media Moderation Team