Sorry to be replying so late but thought I would add to this for others.
UPS often uses brokers in countries. Shipping via UPS always adds the brokerage charge plus the regular shipping cost. The brokerage fee is impossible to determine in advance so I can’t even inform my customers. The brokers also follow the letter of the law and tack on customs fees but seem to ignore the cost declaration and make their own (way higher) guess. So, the duty is out of line with actual product price. This is why I don’t use UPS for my international customers (I’m US based). An 8 oz package to Ireland via UPS added $70 over and above the UPS shipping cost. The price of item was around $50.
Contrast shipping via GlobalPost or USPS. Cost is around $18 USD to Ireland and the Irish postal services doesn’t collect tax/customs duty. In fact, I believe the UK and EU postal services pretty much just deliver the package without charging VAT/Duties/whatever. I’ve heard of maybe 2 cases where they did. That’s out of about 300 packages sent to those countries.
So, the choice is pissed off customers because of significant costs or pissed off customers because of slow shipping. The latter is easier to deal with - at least I can warn them in advance.
Phil