Ha.. Must be snow related. Im from canada as well and this happens often on my montana. Usually happens when snow gets jammed under the hood and the wipers cant get back down. So they go up. Two easy ways to try to do it.
1) Clear snow from the bottom of windshield.
2) With turn the switch on to int, when the wipers get to the lowest position, turn the key to off and remove it. (BE QUICK)
3) With van off gently try to rotate the wipers back to the park position. You may have to open the hood to get them fully down.
4) Turn the switch to "OFF"
5) Turn on the ignition and hopefully the wipers will stay in the parked position.
-OR-
According to the Haynes Manual (Ta-da), they reccomend,
"If the wipers stop in the position they're in when the switch is turned off (fail to park) disconnect the multi-function switch electrical connector. If the wipers now park, replace the multi-function switch.
I think my ideas a bit better and it may take a few stabs to work, but its easier then ripping the steering column apart.