Stop users creating an infopath form if it already exists

I have a form library with the following content types

I have set each form to be saved with the following format Company Name - Network Information

We only need one network information form per customer that's why I set the filename structure this way using the concat function

So once the network information form has been created and information entered I will still need users to be able to go to the form and edit the info.

The problem I have found it if a user does not realize the network information form for the customer has been created, if they create the form again it will overwrite all the info in the original form

Hope that explains it better, thanks