Damaged Differential Upon Install Ring & Pinion

I brought my car into Midas, S Main st Torrington CT on July 25th 2022 to have a new differential ring and pinion installed. The car was promised to me for July 26, 2022. Midas kept delaying and putting of the performing of the job for a full 2 1/2 weeks. I had to purchase the tool for the mechanic to perform the job. When I pick up the car on Thursday August 11th 2022, I leave the parking lot with the car and almost immediately here and abnormal sounding whining or grinding in the rear end. I turn around grab another mechanic who is still there and hadn't gone home yet and took him for a test drive and let him listen to the noise. he assured me the noise is normal and is a break in noise that will go away after 100 or so miles. 150 miles later, the noise is still there and other people who are mechanics NOT with Midas tell me the differential should not make ANY noise at all if the job is properly performed. In short, I had to wait 2 1/2 weeks for a job that was promised to be a one or two day job. The job was performed poorly and there may be damage to my car. Mida grossly overcharged me a price of $850 for a job that is listed as a 5 hour job on the books.