I agree with MAWBROON, it does sound rather odd. Usually shops have to apprehend the person just outside the premises with the goods on them. I would do as other posters have said and ring the local police station to ensure the 2 officers are legitimate. I would also go to the CAB (Citizens advice bureau) for advice. Let us know what happens, I hope your predicament is resolved quickly.
Are extra-marital affairs the answer?
Yes why 12 days.? Phone the non urgent police number and voice your concerns. They will advise you what to do.