Business ProfileforAV Appliance Repair/Service

My dishwasher stop working and I reached out to AV APPLIANCE REPAIR on yelp. Owner ****** schedule an appointment for me next day and sent a technician to diagnose the issue. They request a $75 flat fee to the visit and diagnose and I agreed. The technician showed up next day and checked my dishwasher for a few minutes. Later he told me the issue was the main board and it needs to be replaced and that will solve the problem. He said he didn't have the part on hand and will need another visit if I agree to replace it. He quote me $430 for the job and telling me it not worth it to to do it and suggest me to buy a new one instead. I listened to him and paid him $75 for the diagnose the problem for me and the visit. Later the day I ordered the part online and it was delivered next day. I replaced the part with the new one from manufacture and surprisingly it is still not working. So I contact ****** and ask him why replacing the part won't solve the issue. He first told me that the part I ordered is wrong. So I showed him the correct model# from the manufacture and it match exactly with the part I ordered. Then he told me he will find out with his technician and get back to me. He called me next day and explained to me that it might be other parts that causing the problem other than the main board. This is where I am getting upset with this company because I paid them to diagnose my dishwasher but they failed to perform their job. Instead of going a little further to located the problem, the technician just told me to buy a new machine instead. Like their technician, the owner ****** is not helping me either. He made up excuses from the beginning and didn't want to address the issue. Now I wasted the diagnose fee $75 plus another $100 for the part ordered from manufacture and my machine is still not working. What even worse, I still don't know where the problem is. ****** claims this is not their problem and he can still fix it for another $400.