Hi gardenfairy .
I have and use an Accu-Check Aviva Nano meter tester.
The batteries go on this after about 10months - I ring roche up
request new batteries , record books , control solution etc...
Recieve these 3-5 days later in the post .
You could try ringing roche customer services up and ask
them if there 'is' a switch off function key to your Expert Meter.
Plus request more batteries and explain how often it is needing
new batteries.
If it is unusual they may issue another one whilst your old one gets checked?
To be replacing them every few weeks does seem a lot .
Hope this helps you.
Anna.