SSIS How can I write to a Specific Cell in an Excel Sheet
INSERT INTO [Sheet1$D2:D2] VALUES ('DOB') 


Worked. It appears that you can only use UPDATE if there is already data in the cell and you can only use INSERT if the cell is blank (which it was in my case). 

There was a lot of very useful information relating to this topic in the following link

http://www.winautomation.com/forum/updating-excel-through-sql-statement