It should have a lead with 3.5mm jack plug on one end, and 2.5mm on the other end, which plugs into the headphones. The larger end plugs into your music device. When you plug it in, Bluetooth automatically turns off, and you then get twice as much battery life.
Brilliant! Thanks for this - the only lead I'd found before just actually looking was the charging lead.
I just checked in here before hitting bed and saw this so I'll try tomorrow. Had a bit of a sh!te day today - electrics off. Finally found the problem which was a fried light switch. I didn't know light switches could burn out but apparently they do.