immobilizer ignition key

This happened all of a sudden tonight. Went to get in the car and... 1: Remote key is not opening the doors/demobilizing. 2: Replaced fob battery. Still no No luck 3: Opened door with key got inside and noticed compartment light was really weak. 4: turned key in the ignition and the dash lights...

I've only ever had one set of keys of my zed and just had another scare when I thought I'd lost it. Luckily I found it but made me wonder what if I really had lost it? How would you get hold of a new immobilizer key if your only set's gone? I know my luck's eventually gonna run out and I'm...