2007 "Dodge" Sprinter alarm system

My 07 Dodge/Daimler Sprinter got broken in to. It has a pretty effective coded key and rear cargo lockout security. but no motion/forced entyr/shock sensor security. I went to two alarm installers who said these Mercedes systems are hard to tap in to with an aftermarket system. The dealer wont even return my call (they cant even work on the d**n thing.

Any suggestions would be helpful . My german shepherd wants back into the house at night.