Order with false price

Hello,

I have a question. I made a webshop with Woocommerce with serveral products.
The site isn’t official online, but has a coming soon page. To integrate a payment system I’ve had to set the website online. But within several minutes there was placed an order for a product that was original 696,95 euro’s. But in the order in my mailbox it was only 50 euro’s.

How is that even possible? I’ve searched the whole site for a page that was maybe a concept page but I couldn’t find any. I am a little paniced right now.

Could it be a hacker? But the person who ordered the product paid the 50 euro’s.

https://wordpress.org/plugins/woocommerce/