So what is the guarantee exactly on these Colemans tents?

Stay dry, guaranteed . Well that was why I bought a Coleman Sundome 4 person for the Memorial weekend . It was staked out tight , the guy lines were taut ( my neighbor helped on that) and yet I still had water that had dripped from the walls on one side . I know condensation, it was not that .It was where the water dripped off the fly thing onto the sides. The materials were fine, and according to Coleman everything was taped and ready to go . So it leaked from a fairly hard rain but nothing too bad . So now what ? Coleman seems to have no interest if the material was not damaged from there end . Does the mm water rating mean anything, it is rated at around 450mm and the guys at the camp site said that is a joke to guarantee staying dry. HAs anyone has experience with Coleman backing up an obvious empty promise ? Target will not take it back so am I stuck with a leaky 60.00 piece of worthless crap ? I am pissed because apparently Coleman is all talk and no action. I know it's not designed for really heavy weather just by the flimsy nature of it but c'mon ...why say it can stay dry if it clearly cannot ???