x5 battery dead and replaced but key remote not working

[suali_uk]

My battery was flat after 2 weeks holiday. When battery replaced my key fob won't work to lock and unlock the car/activate alarm. The AA could not reprogramme the key and all fuses are ok. Is there a procedure to reprogramme the Key so it locks/unlocks the car? I have searched but not found any thread for this on this forum so please excuse if this has been answered before. another problem i have is the heater works intermitently now, blower comes on and off as it pleases, not as i want. again the AA could not diagnose this fault despite spending an hour looking at fuses etc. I am new here so any advice appreciated in anticipation. the x5 is 3.0 diesel 2003 Sport model.