Custom MOD in the Works Help Needed

[ryanb4614]

I am trying to creat a mod that sends a certain email when someone checksout. I have the developer that helped me looking into this but he is not 100% sure. I would like someone on her to take a look.
I am getting the following error in the debug:
PHP Fatal error: Call to undefined method order::send_price_email() in /includes/modules/checkout_process.php on line 98

on line 98 it is the following code:
// BOF : PRICE Notice
$order->send_price_email();
// EOF : PRICE Notice

This is causing the customers not to be able to continue the checkout, it brings them to a page not found. I removed the code above and they can checkout...

[gjh42]

It seems self-evident that you are trying to create a new send_price_email() method, and it does not exist in $order. Where does it exist?