"Downgrade Plan" results in mysterious error

The thread title says it all. I want to stop my paid membership after encountering so many bugs here at LingQ.

Even “Downgrade Plan” results in a mysterious error message, see yourself:

I checked your account and I can confirm that you have cancelled your subscription successfully. Your account will be downgraded to FREE on September 4th.
Let us know if there is anything else we can assist you with.

This bug has not been fixed until today. I see this misleading error message. And I see “Your credit card ending in **** will be charged $10 on September 04, 2016.” What am I supposed to believe? Your statement or this message in my profile?

As I’ve said your subscription was cancelled successfully on August 20th and your account will be downgraded to Free tier on September 4th.