Return of goods - UPS charging import duties

I bought a car part from Spain and shortly after ordering I realised it wouldn't fit in our UK car. Without even opening the parcel, I requested a return and sent the item back. Of course I attached the customs declaration which stated this was a return. When the item was in transit, UPS asked me to pay a fee of "around 75€". In repeated emails they could not specify what the charges were for, and when I was still waiting for their response, the parcel arrived back at my door step. It is now two months later and UPS has sent me an invoice over £116 (again, without specifying what these charges are for). Upon repeated enquiry I have learned that the original charges were for import duties. So my question: Is it possible (and plausible) that a return of goods incurs import duties well above the value of the goods themselves? Do I have a standing ground against paying the invoice?

Hi MarleneC,

Customer needs to ask the courier if it is possible to refuse the parcel so it gets sent back.
If that is not possible then customer can look in to paying and reclaiming the custom charges, please see below guidance.
How to apply for a repayment of import duty and VAT if you've overpaid (C285)

Thank you.

Hi, Unfortunately, we could not refuse the parcel when it arrived back. UPS is not charging us UK import duties, but import charges for Spain or Portugal, even now that the parcel has been returned to us. I don't think we would be able to reclaim those...?

Hi MarleneC,
If the customs charges are paid to HMRC, you can make a reclaim if the goods are returned by using guidance here:
How to apply for a repayment of import duty and VAT if you've overpaid (C285) EnglishCymraeg
If the charges have been paid to EU tax authority then you will need to contact them for more information.
Thank you.