Third world service from Whirlpool Service Center

My (pretty expensive) eye level Whirlpool AKZM848 IX microwave oven needed repairs four times since installation 6 years ago. Blown control boards, magnetron issues, etc (at least according to ******** service agents). Maybe we can blame load-shedding.... But my real complaint is the run-around I am getting in my latest experience with them. My MW broke down once again more than two months ago. I duly reported it, opened a ticket, and was told that I needed to pay R598 upfront before they even touch it. The problem is that I am 120km away for a major city, and I have to depend on their subcontrators - some of dubious technical competence. The guy came out, and could not really ID the problem, but said he will see if a new magetron (the most expensive component - I wonder why?) will fix the issue. This was two months ago. My complaints to their service centre are met with excuses, delays, blaming the contractor, waiting for parts, promises about "next week"... the usual third world South African way of arguing away your own incompetence. I'm still waiting, even after threatening to review on Hello Peter. By the way, there is NO way of contacting anybody in some authority in Whirlpool SA (you HAVE to go through the service centre) so they've isolated themselves efficiently form any criticism. I am really exasperated - can anybody offer advice?