Tires Plus Total Car Care review: Service on my 2019 kia sorento

Map sensor replacement cost/retail at auto parts store max $106.00, Gas Cap, $26, Now tires plus is charging me over $250 for the MAP sensor and $56 for the gas cap, which they are getting from Advance Auto in the same building. Manager at auto parts store says Tires Plus gets 10% the price consumers pay, so why am I paying more than double for these parts. I could have walked next door bought the parts myself for less than 1/2 of what Tire Plus is charging me. It gets better, the rubber boot on my CV shaft (right side) cracked and grease is coming out, the Manager say it is $899.00 for a new shaft, plus $135 in labor. They never removed the parts to see if the shaft is bad, nor were than any noises or issues, that I noticed, it was discovered during my normal service, the joint which has no issues, just a cracked rubber boot, $1034.00 plus tax to replace a rubber boot! This store is price gouging consumers, and it is sad, I have been a customer for the past 5 years. Tires Plus Sarasota fl 5812 Derek Rd 34238, You can look me up as a customer and see how long I have been with your company, this really upsets me. What can you do about it, before I contact people, outside of your company to complain?