Unless otherwise provided by law or the agreement, within 15 days means 15 calendar days counting consecutively from the date of purchase. Therefore, if you bought something on December 19 and had to pay "within 15 days from the date of purchase," then you should have paid up on December 30 or earlier. Of course, it might be that your agreement or the seller's policy says something else, but it sounds like that isn't the case or you wouldn't be asking!
Answered on Jan 06th, 2012 at 1:15 PM