I have two children who are slim and tall and any jeans I buy (m&s, John Lewis, gap, h&m etc) are always too short or way too wide at waist. Is there anywhere that you can buy children’s jeans like we buy adults jeans, with a waist and leg length measurement? I though Levi’s might, then saw Levi’s concession in a department store and it was all “age 10” “age 12” etc.