I only recall the name cuz there's been a few threads in the past about payment issues, such as this one:
https://gfy.com/fucking-around-and-b...-dont-pay.html
there's a contact email in that thread in post #8, traffic[at]helixstudios.com, granted that was like 5 years ago so dunno if that will help
either way, good luck and I hope that you get this resolved