My ‘16 Escalade Stopped Running

It happened about a week ago. I had it towed by Cadillac to a dealership. They called me today and said that there were some transmission codes that had to be reset, but that now they have to take the engine apart, and it’ll be another week and a half until it’s ready. They said that it’s either a ‘collapsed lifter’ or ‘the lobes on the cam shaft are worn’. I’m mad because it’s going to be 3 weeks until I finally get the truck back — I’m making full lease payments, they should at least give me a loner vehicle. I asked the dealership for a loaner vehicle, and they said they didn’t have any available and they might have one available this week. Haven’t had this kind of issue before- anyone have suggestions on my best course of action?