Shipments within the same country are not subjected to customs charges. Shipments to US destinations do not incur such import charges because they are shipped within the country.
See UK VAT
Packages from iStyles are usually not subject to customs charges because of the low cost of the package (below the minimum charge) and the shipment via postal mail (not checked by customs) but charges may be levied depending on the regulations of your country's border control.
Generally, all goods imported into a country are liable for duties and taxes unless an exemption or concession applies. Customs charge is effectively VAT/GST and is already factored into the pricing of products and services your country. Products on our web store do not include this charge. This VAT/GST is for the "consumption of goods and services within a country" and may be levied by the customs office of the country when the package is imported.
Please contact your local customs office if you require more information.