Refund

Hi there! On November 5, I requested a refund for 19.99 as I got a free trial in October and was unaware that I even had the trial still as I only opened the app the day I got the trial. I got the refund and canceled my account so it wouldn't happen again.

However, on November 28, I was charged 29.99. Which is confusing as I canceled my plan and didn't even upgrade it. 

How do I get a refund and stop this from happening? I already canceled my account again today on November 30.