Help me find some trousers for ultra skinny DD

[Nutcracker]

My dd1 aged 6 is very very skinny and i cannot find any trousers to fit her.
If they fit her in the leg then they are way to big around her waist, and even a belt doesn't help.
So far i have tried Next, Gap, Asda, Adams, H&M, BHS and many more.

She is now down to one pair of jeans which are actually too big and two pairs of jogging bottoms.

For a couple of years this has been a major problem for me, it seems everywhere now only sells childrens trousers with adjustable waistbands.
My kids have slim waists and you can't seem to find trousers anywhere that don't have an adjustable waistband. They are just not comforatble. If you pull them in to the maximum stretch they are just baggy at the tops and the straps rub on the kids tummies, even if I cut off the elastic and button and sew them up then there is a massive wadge of fabric bunching around at the top.
Is there anywhere at all I can buy trousers for my kids just like the ones you used to get just a couple of years ago? I'll buy from abroad if I have to....
HELP! they're running around like tramps ;-)