Just bumping this with a longer explanation.
Firstly, to check if it has indeed disconnected itself in the easy-to-get-to place:
Lift the bonnet and have someone watch behind the battery while you activate the rear washer jet, if they can see running water coming out of a drainage pipe behind the battery (the passenger side version of the one that's causing the alternator belt freezing problem) then the connector has popped off at the front of the car.
Yours may look different to the pipe pictured, as mine has had the drainage pipes swapped over, but it'll be in the same place.
On the plastic panel that runs under the windscreen there's a grill on the passenger side that's usually mostly covered by the bonnet, the pipe is under that grill and it's easy to get at.
There's a foam block near the grill with a black plastic circle on top of it which is a popper, pull that popper up and out.
Next to the foam block is a foam strip, follow along the strip towards the middle of the car and you'll find the first screw to undo.
Pull the foam block toward the front of the car to reveal the second screw that needs to be undone.
Pull the foam strip forward until you're about half way across the car and you'll be able to see where the plastic panel meets the metal bodywork. You might be able to get into this gap now but you can make life much easier by undoing another clip.
There's a plastic clip on the passenger side of the plastic panel which holds a pipe and stops you lifting the plastic panel very far, it's clipped onto a metal piece that's attached to the plastic panel. You'll need to lift the top of it and then pull the bottom of it down (or vice versa) to get it to release.
You can now lift the plastic panel on the passenger side and get at the area under the grill where you'll find a bundle of wires strapped together - there'll also be a narrow ribbed pipe with a nozzle piece on the end and another piece of the same pipe with a flat end that need pushing back together. The rear washer jet should now work again (provided it's not still frozen, in which case it'll probably pop off again).
The plastic panel will probably have slipped out from under the windscreen on the passenger side, you'll need to make sure it slots back into place before putting everything else back.
Reattach the plastic clip, put the two screws back in, push the foam pieces back into place, push the plastic popper back into its hole and you're done.