Reprogram 2007 Avalanche Key fob

Does anyone know how to reprogram the remotes. Both of my remotes quit working and I have already changed the batteries.

the keyfobs have to be programed through the passanger door module with a Tech2 scan tool, only your gm dealer will be able to do this for you, if you are still under 36k miles it would still be under warranty, otherwise it will run you about 40 bucks for them to program them.