Techie help please?

[delvene]

I've changed my phone recently and would love to keep using my B&O headset.  Only prob is that the headset has a 2.5mm plug and the phone has the new standard 3.5mm socket.  I thought I found the right thing at Dick Smith but it was a mono socket and I need stereo for both.  The helpful guy at Dickies said to try Organiser World but they were liquidated back in April/May  :(  Jaycar website is f'n awful.

Any suggestions?