All mail that enters the UK may be examined by Customs. Normally letters, postcards and parcels containing only documents or similar forms of correspondence are excluded. If you are receiving a parcel from a country outside the EU it may incur Customs charges. Any parcel assessed as being liable for Customs charges will also incur a Royal Mail handling fee of £8. Any goods imported into the UK over the value of £15 are liable to import VAT. Gifts between private individuals over the value of £34 are also liable for VAT. Goods and gifts over these values may also be liable for customs duty. You no longer have to pay Customs duty for goods up to the value of £135, however you will still be required to pay import VAT and excise duty where applicable.
I'm so sorry you have had to pay an additional fee to receive your order! Unfortunately, this is a typical customs fee that is out of our control.