Rip-off?

Today I received something in the post from the Land Downunder. It had been held by the UK Border Force pending payment of customs duty.

The parcels division of Royal Mail very thoughtfully paid these fees of £8.68 (US$13.58, AU$18.41) on my behalf, without asking me. They have then charged me a handling charge of over £13 (US$20, AU$27). Really?!? You have got to be kidding, how can this be justified?