I've had issues with my car key fobs not working.  Previously changing the battery in them made them work for some time, but now after changing both of my key batteries neither is working at all.  Seems like it may be an issue with the signal receiver in the car?  Is there anything that can be done at home to resolve an issue like this?

I had a similar issue, I had my alarm manual and reset the car system using this and I then re programmed my key fobs and from then they worked fine.

Do you have your alarm system manual.?

does the key still work maubaly?

also what fobs are they? if sigma have a read of this,

http://www.scoobypedia.co.uk/index.php/Knowledge/ReprogramAlarmRemoteControls

done it several times to various models