Account not found, lost out on a winning bet

I tried logging into my account to take a last minute bet. I've been using the online platform for many years but then get a pop up saying my username is invalid. I've emailed HB and didn't get a response (still no response) called them but the call kept cutting. I've lost out on a R3k winning bet thanks to them. And there is definitely no way I'd be getting that money back.