Preauthorisation cancelled- but not fully refunded

I stayed over at the radisson blu hotel in sea point. On arrival I was asked to swipe my card for R500 for a security deposit and was advised that on check out the transaction would be cancelled and credited to my account. I now look at my statement, which shows I swiped for R405 and was the only amount credited to me. Why should I be running around for my own money?<br> <br> I had a good stay, but if this is the problem- then I'd rather not bother!