Another APM6855 faulty fridge H problem ?

Another APM6855 faulty fridge now H fridge problem, it ran alot, produces a lot of ice in bottom of freezer. I have defrosted with hairdrier quickly 3 weeks ago, fridge worked okay. Ice has comeback, so have today taken inside backplate off in freezer and removed all ice I can see with hair drier, fan works ok, fridge not getting cold. I have now switched unit off to see if anymore ice gumming up heat exchanger. Any Ideas?!