Thank you for your feedback, and your time on the phone.
As discussed, I arranged for the airline to investigate and they found an error with the link between the airline system and the check-in desk, which resulted in your pre-paid bag not showing. The airline has now has refunded the additional amount paid, which should show within 5 working days.
Apologies for the inconvenience caused and thanks again for your feedback.
Regards
Darrel
ManxFlights