"Company 1" hereby guarantees to pay to you upon your first written demand the amount of any indebtedness of "Company 2" at any tune during the period commencing on 1 September 2009 and ending on 31 August 2012 pursuant to Leasing agreement №... dated 1 September 2009 made by and between you and "Company 3".

Правлю гарантию и нахожу много опечаток. Подскажите, пожалуйста, перевод "at any tune" или, может, здесь тоже опечатка?