I know how

1) If your item really held by kastam, they will send you letter to fill in. There will be 3 choice to pick:
Pick by yourself
Pick by yourfriend (need IC and so on)
Ask agent to take for you (RM50 extra)

Fill the form and fax to the num given

My choice is "Pick up myself"
Why? For example the price for the item is USD1000
so you will be tax 20% and USD200 right?
if you ask the kastam to lower your value also no problem
last time i have to pay RM350+
but i ask to lower down the value of the tax to RM200.
They give me without asking so much.
So, my advice, go kastam and pick up.