I WASN'T REWARDED IN THE RIVALS

Hello everyone last night I reached 20 stars in coach mode in the Rivals. I started from four stars and arrived 20 consequently I should have received 20,000 gems for the prize 10 stars and the prize 20 star but I only received 10,000.

It had already happened to me some time ago that I didn't get 10,000 gems always from the coach mode but even though I contacted the assistance I couldn't receive anything.

This thing bothers me a lot because in total there are 30,000 gems. Can anyone help, please?

Thank you