Oh yeah, 2 things, the ccell2 coils work just fine with 50/50 juice, just they also work ok with 70/30 juice, if u dont mind the restricted hit.
Also, i have no idea why your coils r burning out so quick, as was said previously sometimes they can be hit or miss. Other than that, the rest is common practice...
Make sure u prime them right, make sure to let em sit a cpl minutes in the juice once u install them, dont run them at too high a wattage, dont let the juice get so low that the juice ports are exposed, try not to use ultra sugary juice, buy a pack from a completely different source. Could be your shop got a box of bunk ones. Make sure u r only firing them when u are actually taking a drag. Cant really think of any other reasons