The title explains everything.
I have grouped a few products, like Steel reinforcing sheet and 6 metre lengths of timber into a seperate "custom" shipping rate" handled by our local fleet of trucks.
If a customer adds a length of wood 40kg and goes to checkout: they get " $40 local / $100 up to 100K / $200 up to 200k " etc etc.
If they simply add a tape measure, and go checkout freight calculates to a Australia post airbag at $12 or something. shopify gives priority to the tape measure even though the wood is 6m long and weighs 40 kg... its doing my head in.
Support team recommended yet more apps - but the ones Ive investigated wont do this. urrrrghhh