Cancelling Avast

I am finding it impossible to cancel my subscription for Avast and get a refund. I did no knowingly sign up for this product and it is not connected to my devices yet they took the subscription last year AND the previous year, Each time I tied to cancel but found it impossible and gave up. I am not giving up this year but shot of going to the ombudsman I don’t know what else to do. Any suggestions. Can’t ev en get a chat response from them!