Life long Payements For A Service I'll never use !!!!

I have been batteling to cancel my subscription service with these **********. When following that "cancellation process" it takes you to the step whereby you can change the subscription from premium to free, but when you submit the request it just says "Failed".

I have tried several times with different devices but the result stays the same. They keep taking money from my account and I no longer use the service hence I would like to cancel it.