I had Hagen replace my light unit 15 times before i left them a screwey message that they never bothered replying to (this was alongside replacing my Glo Reptile light unit 5 times!).
Now i would cut my losses and by the newest LED light unit, not with the LED bulbs as the problem is with the fact that the tanks create a lot of condensation and the light units arent sealed for it! The newer light unit can be bought seperately i think? Id try my luck asking Hagen for one as you are a very disgruntled customer but failing that, a Hagen stockist ought to be able to get one in for ya.
http
/www.google.co.uk/imgres?q=fluval+edge+46+led+light+bar&um=1&hl=en&biw=1056&bih=635&tbm=isch&tbnid=xxBwDKffisObAM:&imgrefurl=http
/www.fluvalblog.com/new-fluval-edge-range/&docid=Kob6AFJsyfJKGM&imgurl=http
/www.fluvalblog.com/wp-content/uploads/2011/09/light-bar.jpg&w=1500&h=926&ei=A5rXT-WzDsWt0QXgkpWDBA&zoom=1&iact=hc&vpx=85&vpy=311&dur=120&hovh=176&hovw=286&tx=80&ty=90&sig=103349512573384008980&page=1&tbnh=136&tbnw=180&start=0&ndsp=15&ved=1t:429,r:5,s:0,i:86
Its the one fault of the Fluval Edges (not had any problems with the new led bar!) but tbh it doesnt matter how many times you get it replace
There are also lots of modifications you can make for the light unit if you feel brave! Just google "DIY fluval edge LEDs"
It all depends on how much you like the tank, personally i was determined to make hagen do something so they kept replacing it (i moved house and sold the tank just weeks before the led bulbs came out!). I really liked the tank and would still buy the 46L one again.