Questão jurídica principal
Whether buying the correct bonds above the limit price was a contractual breach or merely an aliud/agency without mandate issue.
Decisão extraída
The bank breached the mandate/commission agreement by disregarding the price limit; this was not an aliud but a failure to follow instructions.
Fundamentação extraída
The bank purchased exactly the securities ordered, so the problem was not the object bought but non-compliance with the maximum price instruction. Therefore Art. 397 OR applied, not the rules on negotiorum gestio.