Hi

Bricklink collect the customs duty and calculate the amount of customs. 

They add it to the invoice total but the amount of cutoms duty goes directly to them not to individual sellers.

As a seller we are sent a customs form and we have to attach it to any parcels or letters for customs in individual countries to see that the customs duty has be collected,

We also have to fill out a detailed customs form and attach as a sticker to the parcel/ letter.

If customs in individual countries does not look at the forms as proof all customs were collected then you should query directly with your countries postal or customs and take up matter with Bricklink directly as sellers do not collect the tax or have your money

Thanks 

Jennifer