I can't subscribe

Hi there,
I tried to upgrade my account for 1 month. I tried three different cards and error keeps coming, saying that I don’t have enough money in my cards which is not true.
What should I do?

Strange. I checked your account and your payments did failed due to insufficient funds.
Can you please contact us on support(at)lingq.com and we will send some additional instructions and try to help you upgrade. Thanks!