Problem with layered navigation block

[Nancy]

Hello everyone 

I am facing a problem with layered navigation block. It does not seem to filter right products. In the following link it fails to present the full price range (left column). You see that the highest price is 20 euros yet layered navigation block has a maximum price of 14 euros. 
What do I need to change to update the prices for the layered navigation block?
https://tonny.gr/βερμούδες/

Thank you!