Key fob re-programming for S-max?

Hi
I've seen the methods put forward for the ford focus etc and I have tried them for my 2007 s-max with no luck. Would like to avoid a visit to a Ford garage but I have run out of options. I replaced the battery in the fob and since then the car hasn't recognised it. My second fob did work but I noticed that the battery was upside down so I changed it round and that aint working now either! Doh!! I've tried the batteries both ways but am now wondering whether I have truly cocked the fobs up! Any ideas??