Question juridique clé
Whether the Federal Supreme Court could enter the appeal despite the unpaid advance costs within the extended deadline.
Solution extraite
No. The appellant neither paid the advance in cash nor provided the required proof of timely payment within the non-extendable grace period.
Motifs extraits
Under Art. 62(3) BGG, failure to pay the advance costs within the set deadline, after warning of non-entry, requires non-entry under Art. 108(1)(a) BGG.