How to cancel subscription / request refund?

I signed up for a free trial of Miro, but it never actually “activated” so I wasn’t able to use it.  After a few days, not the full month trial, I cancelled and deleted my card info.  Cut forward to today, well beyond the free trial and I have a bill from Miro. This needs to be cancelled and refunded.  Any idea how to go about this? I can’t seem to find a way to contact support.