How can i get refund ?

Hello, 

I bought nextdns pro service but we have got some issues. For example, on network my sister can't connect to our home wifi and my father and mother say me:"my phone is not refreshing feeds on social networks.". I think, this is related with my nextdns configuration but i didn't handle it. Because of these issues, i want to get money refund.

I paid money to next dns for their service on 11 June 2022. I have invoice number and it's pdf form. How can i request money refund ?

Best Regards,
Good days, good works...