has anyone had this problem?

I'm in the death Marsh andthere are these alpha Rex' that are way over powered. I can't seem to beat them even with my top squad and have used all my erks. Any advice?  

You should read this topic.  Yes they are way over powered.  The tactic I used was to pick the path that has the least enemies.  Once my squad gets destroyed, I just run through with my leader and use ERKs to keep him alive (until I finish the map).  To be honest, I have yet to finish all of the new maps.  Too tedious.

Haven't even left the deep freeze section / area. Sorr, can't help other than shoot you over some ERKs.

I get plenty of points for leveling mercs in the middle of the frozen areas - route 5.

If you're talking about the bastards I'm thinking of, YES! They were stupid kicking my ass. I ended up just playing it like I do towers, put your best squad on and after every battle, switch the reserves up (even if it's only for 1 step) and get back as much health as you can between every fight for free.

I couldn't believe how many times I died because of those little effers lol.