Appliance Repair by Mountaintop Appliance Service in Blairsville, Georgia

I purchased a new GE dishwasher in February 2016. In October of this year, the dishwasher completely stopped working. No lights and not responding to anything. I called Mountaintop Appliance and Richard came out to diagnose and repair. The service charge was 70. Richard determined it was the main control board. I purchased the part 100 from Mountaintop Appliance and Richard came back on October 18th to install the new control board for 20 as it took about 30 minutes to pull out the old one and install the new one. Everything was working until yesterday, December 5th 2019. Again, 49 days later, the dishwasher is completely dead. No lights no responses. I called Mountaintop Appliance to inform of the same issue with the dishwasher and inquire what my options are. I was informed by Sabrina in the office and Richard that I would be charged an additional 70 service charge for them to re-diagnose and get a new part and the part is under warranty. I of course requested the service charge be waived. Mountaintop Appliance was not willing to budge and insisted it would cost me a week and another 70 to come look and diagnose. I just feel this is not good customer service. We are talking about 49 days. Either the problem was misdiagnosed initially or the part that was installed is bad. Either way, I feel I shouldn't pay an additional 70 service charge. Richard and Sabrina were nice initially but again, I feel an additional 70 service charge is unwarranted.