Custom fees come from the delivery service. So for example, my GP-1000 was delivered by DHL and I had a tracking number for that and they had to drop it round to my house. Since there were no customs fees for that, they brought it straight to me as soon as they got it, but with my guitar that I got from Japan, a letter was delivered to me saying that I had to phone a number or visit a website to arrange payment for the fees. Only after your payment to them had cleared, they'll bring your item to you.
If you don't pay within a certain time, they send it back.
If you don't pay within a certain time, they send it back.