Advertised Price Never Available!

Every time I choose a package - car and flight - the price that's advertised is NEVER honoured by the time it comes to paying for it. ALWAYS this price is suddenly "not available" and I am encouraged to spend more money for the same flight. On top of this, I was unable to actually pay online - AFTER I had spent fifteen minutes filling out all the necessary details and was forced to call the Contact Centre. Not convenient, not quick! Would appreciate if they review and redesign their website to be more user friendly.