I don’t know if this is the app’s fault but...

I tried to buy the full version of this appilcation but when I put in my iTunes card money it didn’t download so I tried again and it said that the card was already used. So how do I get my $5.99 back and the app downloaded? And why didn’t it download? I’m also pretty sure it’s not the app’s fault.

Confused person 12334536 about Screen Recording Tools Lite