The VAT and Duty liability would be on the value of the goods and not the value of the repair and without special authorised customs procedures, you cannot claim these back or defer them.
This may impact companies who have been used to free trade and temporary movement of goods within the EU. If you are not already authorised by HMRC for Inward Processing, you may need to take very swift action.
Further details on this can be found at:
https://www.gov.uk/government/publications/revenue-and-customs-brief-15-2020-vat-conclusion-of-review-of-import-vat-deducted-as-input-tax-by-non-owners/revenue-customs-brief-15-2020-vat-conclusion-of-review-of-import-vat-deducted-as-input-tax-by-non-owners