Fortunate in a way that the switch has failed in the on position.
A relatively rare thing for a Miele or any vacuum come to that.
It may be a mechanical issue with the foot operated control.
Your realistic options are:
1) Carry on using as it is
2) Change/repair the switch yourself
3) Have somebody else do it for you
4) Buy a new vacuum and keep the other as a spare
5) Exercise your warranty rights if possible
