Yes, the Stayokay site allows for secure online payments. Any information that could be considered 'confidential' – such as credit card data, for example – will always be transmitted over secure pages. You can recognise a secure web page by the little key or lock pictograph that appears in the browser as soon as you open such a page. Another indication that the connection is secure is that the address prefix changes from 'http' to 'https'. This means that the information you are transmitting is encrypted using the extremely reliable cryptographic protocol.
Within a specific period determined by your credit card company, you can cancel transactions of which you can prove that they carried out without your permission. Contact your credit card company for further details.