Emily,
I have also looked at your data and was going to write you a solution, but I always struggle with dates in excel.
The dates in the tables are not equal to the dates in price tab. Test it yourself. Look at the first tab-customer 1, row 2 ("A2") is not equal to what appears to be the same date as in tab price, row 1202, 15/04/2013 ("A1202")