Poor service Defy

I recently build a house in Swakopmund. The building contractor makes use of Defy and in May 2021 a glass top stove was supp**** and build in at my house. This stove however since day one gave an error once you switch on the plates of the stove and error could not be found in the booklet supp**** with the stove. The electrician who installed the stove informed me I'm not the only one with this complaint, and that he is struggling with defy, he will take up the matter with Defy and revert back to me. On reverting back, he informed me the error was due to some electronic control panel not working, after which Defy Swakopmund contacted me and informed me they have ordered the part and the electrical element of the oven, which also was at fault. Every week I have to call them as they simply just don't revert back to me. During the week of 9 August, after struggling for almost 3 months, having children and not being able to cook, I threw a hissy fit and on Friday, 13/8/2021 was called by a technician informing me, the parts have arrived and they will be fitting said on Saturday 14/8/2021 at 9h00 and required me to please ensure I am at home, which I did. I in advance asked them if they are sure they will be at my house at 09h00 as I have a doctor's appointment at 10h and they assured me they will be there and be punctual. At 09h30 Saturday morning, there was still no sign of the technician, neither did he or the lady I worked with, answer any phone. At 09:45 the lady called me back on many missed calls to her phone, clearly still half asleep. I asked her what happened to the qtechnician who made the appointment for 09h00, never pitched and also are not answering his phone. She just sleepy said "we will come in a bit" after which I informed her that this was totally unacceptable and unprofessional, that I unfortunately cannot wait, as I on Friday already informed them of my doctor's appointment. She just kept quiet, not answering me, not saying a single a word until I ended call. Up to this moment no one called me to re-schedule, no one even called to apologize for not keeping to their appointment and me as a customer, who have PAID for the stove are the one having the inconvenience. I want this stove REPLACED today! I've been struggling for almost 3 months now and this is truly unacceptable. For almost 3 months I have to rely on take aways and my microwave to supply meals for my family as this company is just not reliable when it comes to aftercare service. I have launched a complaint to them as well but with no response yet. This is totally unacceptable!