If they won't refund you then they're being dicks. Chargeback your credit card if you're in the US. You'll almost certainly win and there's likely no penalty if you don't.

Chargebacks also cost providers money on top of the refund, which disincentives their shitty refund policy.

I run a SaaS company (with a great refund policy) and am part of many SaaS startup groups and it's standard practice to basically refund anyone who asks.

The refund costs way less than the damage to your brand / negative reviews.