Hi mate, there is no upfront fee for delegating SP ... it sounds like you leased 500SP at the same time? Let me have a look at your account ...
EDIT: Mate I've had a look at your account and I can't see any 20 Steem fee/lease from you. All I see is that you've delegated 500 SP and you are receiving daily dividends which will add up to around 18 Steem (the 20 Steem total - our 10% fee)