Now too late to do something but maybe for next time. I have heard stories from the Netherlands where car dealer staff, replace perfectly good parts for new ones and the staff kept the replaced items for their own use.
Before paying and leaving the shop ask for the parts that they replaced, technically they are yours.
If they used them for themselves, this would create a panic as they wouldn't be able to give them to you right away and you know you are getting played. Escalate that with the manager of the shop.