FAULTY MOBICEL HANDSET

I bought a handset which is faulty and returned to the shop several times .now each time i get it back to them they say its ok since i bought the phone i never surely enjoyed the unit because of the problem.i did return the phone in october 2015 and asked the guarantee since all the time i was in problems with the unit. the area manager does not respond back to my emails and now they are threatening to sent me to court. the handset is still with their branch for almost five months now.