http(s)://yoursite.com/billing/?command=check&account=000000
//Response example:<?xml version = "1.0" encoding = "UTF-8"?>
<response>
<result> 0 </result>
<info>
<extra name = "Full Name">some_full_name</extra>
<extra name = "Address">some_address</extra>
<extra name = "Debt">some_debt</extra>
<info>
<comment> OK </comment>
</response>