Alarm siren

[paullus]

I took my car to the dealers yesterday to have the fault codes read to try to find out why I have the problem with the remote central locking I've mentioned in another thread. No fault was shown except a flat battery in the alarm siren which is a separate system. So I still don't know why my remote range is so poor.
Anyway the LED light on the dash is now flashing like mad when the ignition is turned on indicating an alarm fault so I suspect the siren battery is causing that. Furthermore I can't set the alarm off on purpose now either. So:
can the siren battery be replaced?
It's under the nearside wheelarch cover I believe. What sort of job is it to to get at the siren?
Rufe if you read this how much is a new siren please.
Thanks very much.

[rs_andy]

I had the battery die on my siren, found because my alarm kept going off when its cold (turned out to be not that) they can't replace the battery only the siren which ran to £230 at speeds.

Looked at the invoice and the siren was £112.50 + VAT