You need to edit the files in your template's email folder - templates/default/email/html/receipt.tpl or if you are using our templates which I thought you were then you can make a copies of the default template's email folder and put it in each of the neo template folders. Then make the modifications to those instead.
You would be wise to read the documentation on the
68C site with regard to templates and how they work. This is why not all files are present in the neo template folders because they can often the default one. Likewise with the deepsea template etc. Its a tired approach.
Do make a copy of your default template and modify that. Always keep a pristine copy of your default template in your system. When we talk about modifying the default template what we actually mean is your copy of the default template whatever you have called it.