Kernrechtsfrage
Whether the alleged double payment of the security deposit was proven and could reduce the rent debt by set-off.
Extrahierter Entscheid
The tenant did not prove that the later payments to the security account were made by her or for her, so no double payment was established.
Extrahierte Begründung
The appellate court's assessment of the bank evidence was not arbitrary; the tenant bore the burden of proof and could not show the payments could not have come from a third party.