dividing one xls file into many based upon date variable

Hi All

I hope the "general" sub forum is the correct place for this question.

I have lots of xls files that contain 5-6 variables (with around 15,000 cases in each file).
I have in each file ~500 cases per day of the month totaling at ~15000 cases in the file (there is a date variable which a date format in dd/mm/yyyy).
i would like to find an automated way if possible (via macro or other way) to split the big file into smaller files where each file will have all the variables but only the cases for a specific day of the month (totaling in 30 files from the big file).
if possible also auto renaming the files by the date would be a bonus.

can anyone help out with this issue (and save me a good week of my life in hard work )

thanks alot in advance

Z.