General Motors review: unethical behavior (unnecessary services)

Re: 2018 Chevrolet Impala, VIN 2G1105S34J9114849
Dealer: Watson Chevrolet, Tucson Arizona
I had a scheduled January 25 10:00 a.m. appointment with Watson Chevrolet and
when I made the appointment I advised the service department that I wanted an engine oil and filter change and a cabin filter replacement. This was my first time
experience for a service at Watson other than a body damage repair about 10 years
earlier with another vehicle.
This Impala, with 30, 000 miles is in good condition and runs perfectly. I was given Chance Hart as a service advisor. I advised him of what service I had requested(oil &
filter change and replace the cabin filter and reprogram a new key I had bought from Watson)). I also advised him that I had bought the car less than 2 weeks ago and please have the technician assigned to the car to check it over thoroughly. He said the service would be about an hour and 45 minutes or something thereabouts. His estimate for the services was approximately $200 and I told him all right.
After I was there about an hour Mr. Hart came to the waiting room and said he recommended a cooling system flush and a brake system flush.
I was surprised about that on a 30, 000 mile car that looks great and runs great but
his job is to know when services should be performed and I wanted to trust him and
trust my first experience with Watson. Those 2 additional services totaled about $300 which brought the total to $523.09 out the door. After getting home from Watson I reviewed the Service and Maintenance section of my Impala Owner's Manual and was very disappointed to see that Drain and fill engine cooling system
is recommended at 150, 000 miles and Replace brake fluid is 150, 000 miles. By the way the Watson inspection report indicates more than 50% front and rear brake linings remaining. The brakes have been working great. With respect to the cooling
system the coolant was never low and the car runs nice and cool and has never even reached the half way point on a long drive. I like to be trusting and this was my
first experience with Watson service department but I was obviously taken advantage of with two unnecessary services. I haven't mentioned, until now, that I am a senior citizen but I am age 77 and maybe the service staff considered me naïve.