Please contact eFlow and let us know. A new tag and tagholder will be issued. However, you will incur a tag fee of €20.00 + VAT which will be charged to your account. Alternatively, you can contact the person who bought the vehicle to return the tag.
Charges don't apply to the tag, they are billed directly to the registered owner, and usually via a monthly direct debit. The tag owner remains responsible for charges until they alert the operator.