Refund denied for IPVanish - I need help!

I started a trial for IPVanish while I was on a trip. I only used it once! I forgot to cancel the trial, but contacted Apple the same day I got charged explaining the situation and they denied my refund and appeal.

I contacted the developers and they said the only reason why I couldn't receive a refund is because the app was purchased through the App Store - they have a 30 day refund policy on their website, which I had seen before, so assumed it wouldn't be a problem.

This is an expensive app, $89,99 for the annual subscription, which I don't have use for.

I understand it was an oversight of mine to not cancel it before the trial ended, but I requested a refund the next day and it seems extreme for it to be denied when the developer offers 30-day refunds on their website.

Can someone from Apple Support help me with this issue? Has anyone gone through something similar?

Thanks.