The wording of the exclusion is poorly written and cannot be used to decline your claim. There was a common exclusion in insurance policies that declined household theft claims where there was no evidence of a forced OR violent entry. This was meant to mean that the property had to be broken into in order to be able to claim. I believe it was the ombusdman who ruled on a case where the door was left unlocked and someone had pushed open the door to commit the theft. It was ruled that this was a forced entry as force had been used to push the door open. Subsequently all policy wordings were changed to state the exclusion as being forced AND violent entry - meaning that damage was caused (the violent bit). It would appear that your policy wording failes to exclude your claim as the bag did not move on its own and force had to be used to take it (It didnt run off on its' own).I would appeal on this basis and go to the FOS if the Insurer will not accept this.