Help! My BT Freelance XD5500 is stuck/somehow jammed?

My B.T. Freelance XD5500 has suddenly stopped working, with the handsets all flashing up 'Base1' on them. I've been online & found the user guide, but unfortunately, when I try to reset the handsets via the menu as described, I can only get as far as 'set up' on the menu, and it won't then allow me to go on to reset 'default' as the guide states it should-it just beeps at me instead, and then lists a load of last numbers called at me.
If anyone knows how I can somehow mange to get my base station to recognise the handsets again, I'd be very grateful. Thanks