Had one of the worse experience when it came to cancellation of subscription policy. They would not consider issuing the refund of your subscription even on the same day when your subscription renews.
Make sure you cancel your subscription at least 24-48 hours prior to the date of renewal.
I escalated to the supervisor and still they wont issue refund for a subscription that renewed less than 24 hours ago.
Sorry to hear this @murtazatohfa,
but refunds are usually (with any company) only made as exceptions (most times one-time-exceptions) and most subscriptions are not refundable at all by policy. For Stadia for example it seems that there is no refund possibility for the Stadia Pro subscription. In those cases I would always recommend to contact the Stadia team directly to see if they can make a one-time-exception maybe, but as you mentioned you've tried this already.
With Google you have time from Day 1 until the end of the subscription to cancel it, so there is no need to wait until the last day, you could cancel it on Day 1 and use it until it expires and you don't even need to think about it any more.
But well, in Germany we would say "Der Drops ist gelutscht." in this case ("Sh*t happens" or "What's done is done").