Can't downgrade subscription

Hello, I am trying to downgrade my subscription for the time being, but every time after some delay an error window pops up and nothing seems to change. Any help with this?

Hi tkalamov,
I checked your account and we can confirm that you have cancelled your subscription successfully today. Your account will be downgraded to Free level after your current Premium month expire on May 14th.
Let us know if there is anything else we can assist you with.