Did you get the Weezle Extreme +. It's what I use although I too get cold occassionally. I know I read the literature that came with the Weezles and it said it worked best when in direct contact with skin. So, I no longer wear my poly long johns and shirt underneath. But, that may just be that the wicking works best when in contact with one's skin.
I also saw a Weezles vest. Perhaps that can be worn in addition to the full suit.
Another thing is to make sure you are warm before and between dives. Even if that means getting out of the drysuit and into warm clothing, coat, hat and gloves.
Other than that, and I'm sure to get flamed, add a couple pounds to your weight belt so you can add more warm air to the suit. Or switch to an independent argon tank just for the drysuit.
Paula