X5 car starts then dies

[Amateur_carenthusi]

I took my x5 to the dealership to get the vapor pressure and spark plugs fixed. It drove fine for a couple weeks then one day just died in the middle of the road and the service engine soon light came back on.
I feel like the problem is the fuel pump but I'm still learning about cars so I wouldn't know.

The dealership is saying they'll charge me for diagnostics test again if it's not related to the same problem as before which I feel like they're trying to get money from me. I don't really know if it's related to the same problem as before and I don't want to waste money at this dealership after finding a much more reliable autoshop about an hour from me.

So would you guys say they're ripping me off and I should just go to the other place or that it might be related to the previous problem and go ahead with the dealership?