Firestone Complete Auto Care review: Diagnostic test - no mention of cost retail invoice # 108196 store # 798354

My engine light had come on last week and I had it diagnosed for FREE at Auto Zone along with the printouts of the results and the 2 solenoid parts I would need. When I showed up yesterday for my oil change, my engine light was off and I showed the Mgr. all the papers provided by Auto Zone. Even though my engine light was off, he said he can diagnose, never telling me the $120 charge. Firestone diagnostic results came back showing the EXACT same results as I had presented. The parts he wanted were $125 each (240% over the cost from Auto Zone 5 star rating parts.) He tried to tell me that Duralast parts had poor ratings due to failure. I looked up part #'s and 90+% were 5 stars for each part. (160 5-star ratings and 180 5-star rating for the other part. Part # TS1015 & TS1014 both with lifetime warranties. He then said it was the "mechanic" ratings. I asked to see these ratings due to the Duralast having a lifetime warranty on these parts. He could not show me these "mechanic ratings". I felt I was being taken advantage of being I am a WOMAN and he didn't think I would ask such questions. He then looked up NAPPA parts and I did as well on my computer. I found the 2 parts for $59.99 each. He planned on charging me $80 each. (mark up$).
Then he found a kit with the 2 parts for $136 (which includes Firestone "mark-up") plus $167 for labor. I was agreeable to that price. When I picked up my car that day after my $80 oil change, that is when James, Mgr told me my bill was $197.11 ! This is the first I was told of the $120 diagnostic fee ! Since I work for the City of Bentonville, he gave me $20 off, so I still had to pay $100 for the same diagnosis I got for free. What would have been $517 in parts, labor and diagnostic fee should only cost $303 ($136 parts kit + $167 labor).
I am requesting my $100 diagnostic fee refunded due to 3 reasons:
1) The $120 diagnostic fee amount was never disclosed to me.
2) I brought in the free diagnostic results along with the part #'s / names.
NO new/different diagnosis was reported by Firestone diagnostic machine.
3) I am getting my repairs done at Firestone. Best practice is that the diagnosis is free if the repairs are done at the same shop.

I will be getting my repairs done within the next 2 weeks. Per James, mgr, the master mechanic Harry, only works until 3:30pm (shop open until 7pm) and I will need my car for work and will need to schedule the appointment after 4/7/25.
I hope you address my request with attention to customer service and best practice from such a reputable company.
Thank you,

Michele Morey-Pelton
cell#: [protected]
email : [protected]@gmail.com
Date of service 3/29/25
Retail invoice # 108196 (oil change and cost of diagnostic test)
Store # 798354 James
Work order # 108196 (for 2 parts & labor)