php code snippet help

Hello

can anyone help me out please?

I am trying to call a 3rd party short code set up via the do_shortcode process. The coding is below

<?php

// Get amount from querystring value.
$reference = $_GET[ "fullcode" ];

// Output shortcode where needed in template files.
echo do_shortcode('[stripe name="Access Housing" description="Housing Costs"] 
					[stripe_text label="To Confirm, please re-enter your unique reference" Default = '.$reference .' id="Reference" required="true"] 
					[stripe_amount label="Enter Desired Payment" placeholder = "300" required = "true"]
					[/stripe]');

however I am having problems pulling the $reference part through into the shortcode.

fullcode comes from a html form which is then using JS to validate the data entry, but I need the fullcode value to appear as part of the stripe shortcode process.

Someone suggested it would be possible via the do_shortcode process. The php/do_shortcode does work as the remainder of the shortcode does appear on the page when it should, , but I dont seem to be able to pull the fullcode from the html through.

any suggestions?

Thanks