buzescu

My 2008 CLS550 alternator died and while the shop wanted 1300 plus taxes on a new one I asked them if they would install one I bring. They agreed but with no warranty... which of course it is debatable. So I bought a new Bosch on Amazon. At first the dealer charged me a diagnostic, since I wanted to hold the car over the weekend - $190 including taxes. Then they installed the new one and charged me the estimated 2.6 hours of labor - all together another 500$.

Question- is it normal for the dealer to charge the diagnostic then the repair?