I had the microswitch problem a few years ago, it would sometimes unlock the tailgate while the car was being driven, or when the ignition was being switched on.
I got a new tailgate handle, but unfortunately it was the type without the microswitch. A trip to Maplins got me a couple of microswitches, I can't remember the p/n, but the second one is ready to fit and measures 20 X 10.5 X 6.26mm. Cut off the middle terminal and use a*self tapping screw 10.5mm total length by 3mm dia thread. The screw goes in the hole at the same end as the switch button. The wires are soldered on and the microswitch fitted and adjusted. If your ears are good, you can hear the contacts click when the handle is about halfway through its movement. I sprayed the switch with Scotchguard water repellent shoe spray and it has been going strong for several years.
The only special tools needed are to remove the tailgate liner.
Leave the liner off until the adjustment of the microswitch is confirmed by testing.