Immobiliser Issue!

Hi everyone, not sure if you can help me with a bit of a problem I have with my 1997 Corolla Kudos 1.3, we've had it since new and one of the keys stopped working with the immobiliser a few years ago. I had it in at the local dealer and they confirmed that the key was dead and couldn't be re-programmed so I've used the spare ever since. Unfortunately the spare has now given up the ghost also and the engine will turn over fine but the immobiliser kicks in and won't let it start. I've done a lot of work on it including a full gxi bodykit with bumpers, si bootlid, colour coded elec mirrors, 17" fox alloys, clear indicators etc but now it sits in the garage with a flat battery for months at a time and hasn't been on the road since 2010! So just wondering if by getting a second hand ECU from a slightly older 1.3 that doesn't have an immobiliser whether that would work instead of shelling out a lot of money getting new keys only to have the same issue again in the future?
Thanks in advance!

have you looked to see if you can find an ecu from the same year corolla but one that is an import?
have you tried to get it bypassed?

the immobiliser box is under the drivers seat iirc

Thanks for that, I might try calling an auto-electrician then to see if they can bypass it, unless this is something that I could do myself as I'd rather it didn't have one! Thanks

Just to help out if anyone else has this issue too, I had an auto locksmith come out today and had it confirmed that the second key was now completely dead too so was stopping it starting (may be due to age or being dropped etc). I managed to locate the immobiliser box (on my year I found it was located behind the dashboard in the very centre) and using this he managed to program 2 new keys. After this the car fired straight up. It is odd, the keys don't look like they have chips in them, but they do!! Apparently it should have had a grey master key which would have made the process much easier and less expensive but I don't recall us ever having this.