I booked some tickets for an event for my daughter's birthday, unfortunately she now has to isolate so we can't go. The event organiser is only contactable by email. The website says in the event of having to isolate due to Covid please contact them and the will endeavour to rebook you on a different day and if they are unable to refunds will be considered on a case by case basis. I contacted them last week and they haven't replied, we are due to go today. The tickets weren't cheap. I booked on a credit card if that makes any difference. How can I sort this out?