Company incorrectly declared purchased goods as "gifts" due to a "glitch" in their system

I have been using a Japanese proxy service company (sender) to purchase used items from Japanese websites for the last two years. When I request my items to be packed and sent to me, I always ensure that the value is below the £135 threshold, and the Japanese company declares the items as "other", given the nature of the purchased items, and lists individually all items and their cost. I have suddenly been charged 20% import vat on four packages I received via FedEx, because the sender incorrectly declared my items as "gifts". I contacted the Japanese proxy service company and they admitted it was a "glitch" on their system and that they should not have been declared as "gifts", but they said they cannot do anything. The items were clearly paid for as their individual value is stated in the declaration form and the sender is clearly a company on the paperwork - so they are obviously not free "gifts" sent from one private individual to another. All packages are below the £135 threshold but obviously above £39 in value. I contacted FedEx to say that there is a mistake in the declaration form and they should not have been marked as "gifts". Is it possible to amend or dispute the VAT import charges, when this is clearly a mistake by the sender on the declaration form?

The £135 threshold only applies to a customs duty exemption for goods in a single consignment. There is no VAT exemption. Import VAT is due on the total import value of the goods. In addition I should point out the description of other is not acceptable as it does not accurately describe what the goods are. The exact nature of the goods should be mentioned. You should check with the carrier as they usually provide guidance on this as vague or generic descriptions can cause hold ups. Nor as you say goods which are not genuine gifts between private individuals be described as gifts. Even gifts should be described further so the exact nature of the goods are known.

Hi,
Customer can look into paying charges and request a repayment using form C285.
More information on below link:
How to claim a repayment of import duty and VAT if you've overpaid
Thank you.