Just bought car - Remote unlocking woes

[thefunkygibbon]

Hi all, first post :-)

Just came back from purchasing my first Porsche, a 986.2 and whilst the remote seemed to work fine when i looked at the car before buying. I've come home to find that the 2nd key i have doesn't seem to work to lock/unlock the car (it can manually open and start the car)..

Also the 1st key it seems really hit or miss whether it locks or unlocks. sometimes it will happily do it. others i'm standing there pushing the button for a good 20 seconds before it bothers locking.

I've changed the batteries in both. The red lights are flashing as expected with each press on both.
Really don't want the expense of buying 2 new keys at £150+ a pop.

Any ideas?
thanks in advance