what make is the fridge freezer? usually that smell is caused by a liquid spilled inside the fridge. if you pull out the fridge and check the evaporator dish at the back you should find that that is where your smell is coming from. if you get some milton cleaner and wash the dish with a cloth your problem should be solved. if not keep getting the repair man out until the smell is gone. if its only 3 months old, the warranty will cover this until it is sorted out.