When you remove the stem there will be a minimum insertion mark, raise the stem to this point and thats the max height. In my experience shops generally set the stems very low as aesthetically it is more pleasing.
thanks! i have raised it to the safest limit now..only got a "little" more height,have a 19 mile eride home to assees whether it makes any difference! i think possibly the "riding style" is having an impact...not ridden a "road" bike for donkeys years,been moutain bikes all the way 'till now..i guess i will adjust:)