defy model c385 numerous problems from december

i have bought defy fridge model c385 from makro on the 10 april 2015,from day one the fridge freezer was working fine.from 27 december 2015 the fridge was not cooling only ants coming inside the fridge ,food was getting spoiled ,i callled defy repair center-reffrence job number 484999,the repair tecniction came out ,they said nothing was wrong,then we called repair center again i reported ,then another tecniction came out on 11/02/2016 the tecniction replaced thermostat,still the problem fridge is not cooling and ants is in the fridge ,we are so fed up of this fridge ,i request defy to take this fridge away asap ,replace me with new fridge ,