Modules & VBA :: Prevent Duplicate Records To External CSV File From Form

I have some code which creates a record in an external csv file to provide information to upload a vehicle to the website. It works fine with the exception of creating duplicates when, for example an option to amend a record is given to the user before continuing to a new record. The option has to be in place in case there is an error in the specifics of what is important to be recorded in the database and under such circumstances the form code allows the user to tab through the form and correct any errors, but this creates duplicate entries in the csv file as the user has to pass through the 'SavePrintVehPurch_Exit' button a second time after corrections are made.

I am wondering if there is a way of altering the following code to effectively look look to see if the csv record exists and if so correct any changed field information rather than create a whole new record or create a new record where the record does not exist - The record in the csv file is determined by the 'Me.VP_VehRegMark.Value '.

Private Sub SavePrintVehPurch_Exit(Cancel As Integer)
Dim fileText As String
Dim fileName As String
Dim fileNumber As String
fileNumber = FreeFile

[Code] ....

I am wondering about introducing the something like the following ( but can't work out how to clarify comparison of the fields)

If Len(filename(fileText)) = ? Then
Do not change entry
Else
Overwrite the new detail