<code>&pay=groupbalance</code> for a payment request collecting the outstanding balance for the group booking (the default)
<code>&pay=groupbalance&pc=25</code> pc can be used to specify a percentage of the pay amount, for example here 25% of the groupbalance will be collected.
<code>&pay=na</code> for a request to collect credit card details without showing an amount
</code>
Examples: