As some of you are now aware, the biggest problem with the s-max is the poxy alarm!
The problem is caused by water getting into the alarm sounder module which is located under the front ns wheel arch.
The only cure is to get the alarm sounder replaced at the dealers.
In the mean time, fuse F26 in the central fuse box provides the power to the alarm sounder. Unfortunately Ford also provided this sounder with an internal battery, so pulling the fuse will not instantly silence the alarm but will eventually as the battery drains and will prevent the alarm from sounding again while you are waiting for the part to arrive at the dealers! (The wipers will also return to normal function).
To access and identify the fuse, you need to remove a small piece of carpet under the glove box held on with 2 plastic fasteners (these just pull off) then there is a small latch which when turned will release the fuse box which is hinged at the back so just pull it down far enough to get your hand in.
Fuse F26 is a 5A and is third from the bottom on the left.
Hope this helps.