Possibly the battery or the fob is faulty. A duracell CR2032 is less than £2 in ASDA and you can change it yourself which is the cheapest thing to try. The key won't forget anything because its the car that remembers the keycode not the key. I also have 2 extra remote keys which I bought off fleabay and programed them myself as shown in the manual. You have to get the key cut at Ford which cost me a fiver last time. I have another one to cut soon.