Australia recenlty rolled out some pretty simple "applies to everything" rules. Whatever price you advertise, you have to sell your product/service for that price.

You can only charge extra fees if those are optional fees for additional services on top of the product you've advertised. If they are mandatory fees, then you have to sell the product for the lowest price you've advertised. And you can be forced to issue partial refunds to every customer you've ever had who paid too much.