Air conditioning unit remote control problem

Question

Hi! Our National/Panasonic split type airconditioning unit is over 7 years old. The remote control conked out yesterday and the Panasonic Service Center said they don't carry replacements for our model anymore.

I was wondering if there's a way to salvage the remote control since the AC unit still works perfectly. The remote turns the AC on and off but a) the display/LCD goes blank unless you press a button; b) the temperature gauge is stuck at 25-27C; c) if you try to change the mode and fan level, it keeps resetting. The batteries are new so it can't be that.

Help, please. The Service Center barely stopped short at saying we should just replace the unit.