ok.. had to take the car back as the calipers were binding slightly and luckly no damage to the disks
Garage were great.. they did a full strip down of the caliper and silicone greased all the bits. They did a fab job and when it came to pay it was a big fat 0, nada, gratis!
brakes feel much better
so.. if you have a warped disk then this could well be the problem