Omio complaint: Ticket refund or credit note

I booked a ticket from London to Birmingham for the 153 returning the next day. I was going to attend a training. However, due to the teachers’ strike, my training was cancelled, I was informed yesterday. I contacted Omio by phone because they do not accept my request via the app, and was informed that there is nothing they can do. Apparently, I chose a ticket that does not give me a refund. I explained the situation is beyond my control and I would be happy with a credit note as the training will be re-arranged. They have a blanket response, NO, there is nothing they can do, and worse still, there is nobody else I can contact to plead my case or to leave a review. I found it to be appalling customer service. I am really frustrated with the lack of support they offer, they have attendants that are polite but useless as all they can say is ‘ I am sorry’.
I. Ribeiro