2009 Chevy 1500 Silverado Hybrid

Hello! We have a 2009 Silverado Hybrid and are having some problems with it. It’s battery, or something else, can’t seem to hold a charge. We don’t use it but maybe once a week. But when we go to move it after a week, it has no juice. By that we mean we can’t unlock the car from the FOB or start it. It’s completely dead. We’ve taken it to the dealership where we got it and they’ve told us nothing is wrong with it. They’ve told us we need to move it more often to charge it because of all the “modules” that draw power from the battery. We’d like to know if this sounds right, what we could do differently, if you have any other ideas as to what’s wrong or anything else you think would help. Thanks and we look forward to hearing back from the community.