Get your billing in order, Supersonic

I've been going from pillar to post trying to get an invoice. I don't understand why I must beg Supersonic to bill me. I've tried the portal but the loading spinner has disabled everything on the screen. I've tried calling the call centre but the guy told me that they could only invoice me after the 25th of this month, now that the date has passed I have been waiting forever to get through to an agent. Gosh, this is the most frustrating experience ever.