Log into your account at WP>Power Up>Click on the respective Game Account/s>View Transaction History>In-Game Item Purchase History. Set the start date and you should get a list of all the items bought on said account along with the dates
Thank you for the help.
Unfortunately I found that I spent 1000kp on 14th and 1000kp on the 15th. You think they'll let it slide and give me the costume still?