Hi,
Can you hear the locking motor operate when you press the glass release button? If you can open the tailgate part way and press the glass release button whilst pulling up on the wiper assy or press from behind around the glass lock area, mine has had the locking spindle misadjusted/ loosened and the metal plate had sheared. This is how I got mine open - it was a real pig. I hope this makes sense.It did take about 30 mins and alot of messing with.
On the aircon situation, how long has it been without gas for? you have to be careful as the seals can dry out etc... I had mine tested earlier this week and have been told that the condenser has a massive leak - least of my problems at the moment.
It will get sorted
Jon