Picnics in the Park - dont keep promises

Bought tickets for an event, requirements around covid changed post ticket purchase. Would be required to incure additional costs and thus was promised a refund (this was in writting). Sent all the details and since then nothing! Complete silence. Doesnt answer phone calls, emails, whatsapps. I even tried to be responsible and agree partial refund, but no response. No common decency to just deal with the situation. So sad, wont support events hosted by this company as there is no trust in what they promise and deliver.