Stax Affiliates - 6 months without getting paid

I´ve been waiting 6 months to get paid for my earned commission. The invoice was sent 6th of december 2024. They paid the 1st invoice without any problems, but then they have avoided the payment of the 2nd invoice. They do answer when I text so they are not completely avoiding the subject, however now it´s way overdue and I believe the payment should be made right away. Hence I need to go forward in this forum. Amount is 525.28 euros.

Dear Stax Affiliates,

Please let us know if there are any updates regarding this ongoing complaint. Please note that, in case you fail to respond within the given timeframe, we will consider your case unresolved and it will be closed accordingly.

Thanks in advance for your cooperation.