Yeah, I hate that Parcelfarce bullshit with a passion. I had a service fee levied on something which was zero-rated for import duties, but they charged a handling fee plus duties anyway. When I called them and said so, they basically blamed me for not writing ‘customs duties will be handled by addressee’ on it and sent me a nice form to reclaim the tax, with the proviso that they’d be keeping their handling fee. Seriously, the UK is turning into a third-world shithole populated by skimmers and scammers.
This is the basic reason I oppose import duties on principle, especially systems that involve complicated rules: they tend to evolve into a disgusting cesspit of corruption and official skulduggery.