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i don't have an 'invite' now that i'm premium that's gone. that's why i asked them on twitter if it's worth me still having my code now i'm in, like what would be the usefulness of it kinda thing. . ;)

Oh, look at me know-it-all, LOL
That would be totally counter intuitive (but sadly not surprising) if they took away your chance to earn a referral bonus now that you actually invested money in them...

just a design flaw and no doubt rushed coding exercise to increase signups either way useful card for right now ;)