Defy - worst service ever

I purchased a Defy fridge three months ago and every time the compressor switches off it makes a loud sound. They have sent two technicians and they both say it is normal. My sister has the exact same fridge yet hers does not make this "normal" sound.

I then decided to record the sound, which they admitted was not normal but said because it did not make the sound when they were there I will have to call them again. Worst service ever...I would not recommend their fridges.