Talk about a ripoff on price

I have a Dart Contol 250G, which is a large heat sink with a simple plastic cover. I bought it new about 1 year ago. The cover has cracked
at the mount holes on the first one, and it was replaced after a lot of hassle with DART. The replacement cover that was sent is now cracking at the corners. I could see if this control was in use or setting in full sunlight and weather, but for the most part it has been in a box and put on a shelf without any direct sunlight or chemicals around. I called today to order a replacement cover and they want $68.50 plus $12.00 shipping for this el cheapo cover that is more than likely going to crack apart again. The cover is nothing fancy, just a sloped recess formed piece of plastic.
I am half tempted to cover the entire chassis with a piece of aluminum or plexiglass etc, and mount the potentiometer and on and off switch in another remote mounted box before I spend that kind of money on a problematic cover as such.
Any ideas on how to repair these cracked covers? I have tried all kinds of glue, but the plastic is very thin and the edge is very small that is prone to cracking so there really is not much meat there to work with. Instructions state to tighten the cover no more than to the point that it makes slight contact with the chassis gasket. I know the covers were not overtightened, and look at it as more of a cheap design flaw or improper materials used to make the covers oout of.
Any suggestions appreciated. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy.
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