For anyone browsing this for reference the photographs do show the correct fittings (Thule 3030) for an S-Max 2006-2011. The tall hard plastic pieces shown partly inserted into the roof recesses then have hard rubber feet surrounding them as part of the kit. This hard rubber should stand just off the paintwork to avoid marks. Looks odd but works. I have found that the Ford Galaxy (2006-) kit also works but ends up bolting straight into the roof recesses and the rubber pads sit on the roof.
With regard to the key locking but not unlocking: It might be that he door lock has been replaced and uses a different key. This model uses the Tibbes type key - all Tibbes keys will perform the lock function on any similarly equipped car but not the unlock. Just a thought! As the previous poster said - the heater could well be the electronic valve which is prone to seizing on this model Fiesta. Ka's and Transits use the same one. I've replaced them with pattern ones from Ebay.