Jeep Liberty Parking Brake

I recently had my rear brake pads replaced by my Jeep Dealer. This was the first time they’ve been replaced. Now my Parking brake doesn’t work nearly as well as it did before the brake job. I’ve taken it back to the dealer 3 times and the keep telling me “this is the best it gets”. They threw me a bone last time and replaced the brake lever but the results are the same. The weird thing is, if the Liberty is facing uphill, the parking brake works perfectly. Only when the Liberty is facing downhill, I need to pull the lever aalllll the way up, as hard as I can, and it still doesn’t hold hardly at all. The other thing, when the vehicle is moving forward, while I’m driving, I should be able to use the parking brake in an emergency, but even going about 10 mph, again when I pull the brake, it hardly grabs at all. Any ideas???