You mean covering their admin costs for collecting import duty and VAT on behalf of Her Majesty's Revenue and Customs Sevice because HMRC prefer to outsource that particular task?
If you have many hours of free time, and can convince your preferred supplier to fill out the correct forms, you can avoid paying the equivalent of less than one hours minimum wage...
I will happily provide the information on how to avoid this onerous charge for the very reasonable price of 1 Bitcoin +VAT @20% .