Am I using the correct batteries in my remote?

I have recently purchased a Saab 900S that has an alarm system installed by Code Alarm. My remote for the alarm system has got 4 A13 hearing aid batteries in it and they only last a couple of weeks. Are they the correct batteries?
These amount to 5.6 Vaults is that enough?
If they are not can you please advise me on the size batteries i will require.
Thankyou
Chris