Munchy has it right. You need to sit down and talk, all of you. Make sure that all (or at least most) of the Players agree that it is too hard. Only then can you go to the GM and see if he can dial down the death-dealing a bit.
As for the different styles mentioned, if the
"this is a heavily guarded rooms (there are ten guards of eighth level not matter what level or how many party members there are)".
style, ask that he give better hints as to what might be too tough for you.
Example: The Knights of Death & Destruction (KoDD) are an elite order so would be too tough for low level PCs to handle (except, maybe, a single wounded knight caught by surprise
) so the GM should ensure that they know this. Easiest way is to show them handling something that would be tough for the PCs without much problem. Cultural knowledge and other societal information would help here as well. You hear enough stories of the KoDD riding off and destroying (hence, the name) numerous dangerous foes, you will be less likely to take them on.
Another example: The monster is too tough for the PCs so outside it's lair are the bones and detritus of other fools who have tired to slay the beast. Have one or more suits of armor known to be worn by the KoDD among the detritus - that should make them back off.