Is this how you usually park? I mean is this a first time occurence?
Your shifter interlock linkage may be out of adjustment or force bound by the weight of the VX and the park pawl in the trans.
You have a couple options:
See if you can have a friend or neighbor push/ bounce at the back while you try shifting (key in "On" position and engine NOT running) and try shifting into neutral, if it shifts apply e-brake.
Remove the shifter handle and console section to expose the shift interlock and linkage and temporarily disable.
Not too sure about this one but I think there's a solenoid as part of the ignition/ brake/ shifter interlock, try temporarily disconnecting it or your battery.
Start using your e-brake when you park on hills.
Hope this helps.