The biggest problem with the S-max is currently the security alarm. It appears to be caused by water ingress into the alarm horn (located under the front nearside wheel arch) and currently the only fix is to replace the sounder with a new part from a main dealer.

The sounder is powered by a single fuse (F26 (5A) third from the bottom on the left) located in the Central fuse box. In order to access this you'll need to pull off the small carpet trim under the glovebox and then turn the release latch - this allows the fuse box to drop down on its hinge and access to be gained. However,  in order to be Thatchman approved all new security systems need to continue to work even with power disconnected - as such the sounder has an internal battery, so removing F26 isn't an instant fix however once the internal battery is depleted the alarm will finally be silenced!