Linksys Cable / DSL :: DG834GT Website Blocking By Keyword

WAG320 allows website blocking, to enable this you can use a keyword. I would like to use this function to block anoying advert sites (in the same way I could with my Netgear DG834GT) - However the way this function has been implemented is less than ideal.
 
e.g. when a site is blocked by the router, the router does not return a response - this is great until that site forms only part of a web page that is permitted. What then happens is the web page takes forever to load as the responses have to timeout for the blocked components.
 
The way this function *should* have been implemented, is the router should return a blank response for each of the blocked sites. Netgear do this and it works a treat, they even put up a banner saying "Website blocked by Netgear".
 
This is such a simple feature, why has Cisco overlooked this and how do I go about raising a product enhancement ? I've been through the helpdesk which quite frankly is a farse, they asked me to reflash my firmware which surprisingly didn't resolve the issue - they then told me to send them the unit back because it must have a fault !?!? (and I have to pay for postage of course!) I explained the issue about 5 times, but the operator on the other end was just a script reader and I could not speak to an engineer - very poor.