withdraw money from Lightspeed Panel Survey account

I have an account with the company Lightspeed Panel Survey (which purportedly pays you for taking part in surveys) and had built up a bit of money from doing their surveys, which I attempted to withdraw earlier today. I requested that the money be sent to me via PayPal, but didn't claim all of what I'd earned. When I tried to log onto the sight later it didn't let me, and says my email address isn't in their database. It's definitely the same email address I always use, so why has it deleted my account?
Has this happened to anyone else? Is it a swindle to get out of having to pay me, or just a glitch? Any help greatly appreciated!