Batch program to get file based on date

Hi,
I have to copy a file from a site on to my local machine, the file will be of the name eg."Graduate20071231". I have to get yesterdays file today and fridays file if it is monday. I am using the below script. It fails when monday falls from 1st to 3rd of a month and it also fails on 1st of every month.

Please help

echo on
@REM Setups %date variable
@REM First parses month, day, and year into mm , dd, yyyy formats and then combines to be YYYYMMDD

FOR /F "TOKENS=1* DELIMS= " %%A IN ('DATE/T') DO SET CDATE=%%B
FOR /F "TOKENS=1,2 DELIMS=/ " %%A IN ('DATE/T') DO SET mm=%%B
FOR /F "TOKENS=1,2 DELIMS=/" %%A IN ('echo %CDATE%') DO SET dd=%%B
FOR /F "TOKENS=2,3 DELIMS=/ " %%A IN ('echo %CDATE%') DO SET yyyy=%%B

@REM get the first digit of day
SET dayfdig=%dd:~0,1%

@REM get the 2nd digit of day
SET daysdig=%dd:~1,1%

@REM get the name of day such as Mon,Tue,Wed etc
SET dayname=%date:~0,3%

@REM Check for day of the week
@REM If day is monday then download file for friday otherwise for prev day

if '%dayname%'=='Mon' goto getdays-value

if %dayfdig% LSS 1 goto calculate1-days
SET /A ndays=%dd% - 1
goto cal-finaldate

:getdays-value
if %dayfdig% LSS 1 goto calculate-days
SET /A ndays=%dd% - 3
goto cal-finaldate

:calculate-days
SET /A ndays=%daysdig% - 3
goto cal-finaldate

:calculate1-days
SET /A ndays=%daysdig% - 1
goto cal-finaldate

:cal-finaldate
if %ndays% LSS 10 goto final-days
SET mdate=%yyyy%%mm%%ndays%

if %ndays% GEQ 10 goto download

:final-days
SET mdate=%yyyy%%mm%0%ndays%

:download

SET mdate=%mdate: =%Start Free Trial