Electro Service - poor service - no post repair warranty fulfillment

I contacted Electro Service to repair my upright AEG Arctis Frost freezer which had a compressor issue brought on by load-shedding. The technician attended to the fault and replaced the compressor on the freezer, but the compressor was and is making a load noise which was not there prior to failure. I subsequently re-contacted the technician via WhatsApp, tried him telephonically and even contacted his office number as well, and on each contact, they committed to come out and attend, but have not been since. The technician is no longer answering my calls. I now have to contact a different supplier to remedy the situation as this company is not responding, even though their repair is supposed to carry a 6 month warranty.