Many thanks for your reply - yes that's right. So what I'm looking for is a confirmation email that says "test123" in the hidden field with the name "quote_details" but at the moment it's not being written. I'm testing it by filling out the form, submitting it and then checking the email to see if the field has "test123" in it.
My first steps would be to ensure that your custom fields are created, named, and referenced/targeted correctly. This seems obvious but its a small thing that can be over looked if you've got a tight deadline. If the field is referenced/targeted incorrectly it will not be added to the DB on submission.
I've got little experience working with forms in this way, but it looks like your onFormSubmitted and the onFormReady are doing the same thing in terms of updating the data value. I don't think this is an issue, but rather a redundancy that we probaly don't need muddying the waters. Especially if this is a hidden field that the user cannot change.
Many thanks for your reply. Definitely - fair point, I've checked it and it's using the right name. I was trying a few different options to see what stuck which is why they are both 'onFormSubmitted' and 'onFormReady'.
Do you have an example of a form that you've made in the past? I could use that as a basis. It's really strange, seems such a simple thing but it's just not writing the value to the field - bizarre.