It sounds like there has been a bit of confusion with the height gains.
Our normal raised height kits are 40-50mm above standard.
If your original suspension has settled 20mm in the rear, the actual lift may be 70mm which is 50mm above standard.
The height relationship between front and rear is maintained as specified in the National Code Of Practice.
the original relationship between the front and rear suspension heights must not be changed and therefore the front and rear suspensions must be both raised by the same amount