Key legal question
Whether the Federal Supreme Court could enter into the appeal despite the unpaid advance costs.
Extracted holding
No. Because the appellant neither paid the advance costs nor proved timely payment within the non-extendable grace period, the court could not examine the appeal.
Extracted reasoning
After a warning under Art. 62(3) BGG, non-payment of the required advance costs entails non-entry under Art. 108(1)(a) BGG.