Zafira power sounder batteries?

Hi, I have a problem with my Zafira car alarm and power sounder going off for no reason.
I have read on forums that the cause is that the batteries in the power sounder need replacing, but the batteries (made by Varta) are no longer available from cellpacksolutions.com. I spoke to cellpacksolutions to see if theres a replacement and they told me that people are buying and fitting a battery - 3/V150H/4p.
Just wondered if any one else has fitted this battery to a Zafira?
Thanks for any assistance.