Create an Invoice email from a submitted booking form in PHP

Hi everyone,
I need to create an INVOICE out of a booking form already existing.
When the submit button is pressed, I need to send an email to the customer in a template that I'm calling 'INVOICE'.
Actually the email is already set but the data is sent just via plain text and not html and I think as a string.
Unfortunately the booking form has been 'custom' created and the fields for collecting data are just in a form of raw data. (and I cannot get single field with $_POST...)
If someone can take a look at the code I attached and give some hints/solutions it will be great!
Also, if you need more data I'll post more files.
Cristian CarattiSoftware developerAsked:
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Just confused with the query.
Please confirm if my understanding is right.
You would be sending an Email which has form within it which would when posted would provide them PDF.
when client fills the form via email body u don't get post value
Cristian CarattiSoftware developerAuthor Commented:
Thank you for your attention.
There's an existing form (pre_booking-test.php attached in my first post) that collect data from a customer. if he choose to pay by invoice, the data is collected and sent via email (phpMailer) as plain text to the website owner.
He then organise this data in an excel file and send it to the customer.
Basically I need to modify the form in a way that the data is collected and sent to the owner of the website in a form of html template and it should resemble an invoice which all the fields filled up.
I can create an html template email and manage the Phpmailer but I cannot get the data into it.
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