Has payment been taken for the pre order and are you using the same account you placed the pre order on?
You may need to speak to customer support to resolve this.
Contact page - https://www.playstation.com/en-gb/get-help/contact-us/
Twitter - https://twitter.com/AskPS_UK
Live chat - https://www.playstation.com/en-gb/get-help/help-library/apps---features/playstation-uk-live-chat-support/