Money paid to pay my fines but the fine still in force.

I am resorting to this means of contact in hope that I can get some sort of response from Pay my fines paid my fines. They admittedly resolved the majority of the fines as expected, with the exception of 1. They took my money for the fine! Provided me with an invoice as proof of its payment , with a statement resolved now on the site, but they still show the fine as in force. AS does ARTU , This has now resulted me in not being able to renew my licence without paying again. I have emailed Pay my fines on all of their addresses! Over the last 2 weeks ( No response ) If they cant resolve the fine then ethically they should give my money back. With this experience I would thus far advise caution when dealing with this site.