They do offer extra space for referrals actually (0.5GB/referral up to 6GB free on top of the 2GB free or pro plan). I had already referred a bunch of people so

They do offer extra space for referrals actually (0.5GB/referral up to 6GB free on top of the 2GB free or pro plan). I had already referred a bunch of people so I emailed them and they quickly credited my account! Try sending them a nice message, they seem to be pretty on top of customer service :)