Hm, what kind of message you receive when trying to request a refund? Could you please show me a screenshot so I can investigate?

Also, as wolfsite said, you can fill this form: https://support.gog.com/hc/pl/requests/new?form=orders

Hm, I will forward this for investigation.
In the meantime, please consider using your PC instead your mobile device and fill this form: https://support.gog.com/hc/pl/requests/new?form=orders