The time is not totally relevant, but the date is.
You should still be able to pass this via your insurers who inturn can contact the store and proceed with a claim. If the store have confirmed liability, have you not received this in writing or at least taken the name of the person that told you, including the date and time???
As their property has been damaged ,thus causing damage to yours, you can still claim from their insurers.
Imagine a 3 car incident, A hits B in the rear, which result B hitting C in the rear. C will claim from B and B from A.