GENERAL CONDITIONS OF CARRIAGE FOR PASSENGERS AND BAGGAGE Section 9.3.3.

Sorry Your speakers are not covered. Sorry you have learnt the hard away about travelling with electronics - in hand carry, or via freight. Never check in luggage (bubble wrap is pointless).

You might get the damaged suitcase and incidentals repaid, but not the speakers. They aren't responding anymore as you are demanding something that they are not obligated to give. Not great CS, but they should at least transfer the balance while they continue to argue their point with you.

The other problem you are having is the claim on your insurance - if that's been paid by insurance already, the airline doesn't actually owe you anything. If you have told the airline as much, that could also be why they aren't responding.
Clarity