I drive a 2012 Volvo S60 t5Later back I had the check engine light come on or it’s been on for a good while took it to my trusty mechanic had a diagnostic taken. Said only two things to get done which was a new battery to $234 and a oxygen sensor $345. I got the oxygen sensor done and I was going to wait later on to get the battery since mine isn’t dead yet. Fast forward took my car to the Volvo dealer for another diagnostic said that my timing belt and serpentine belt was installed incorrectly and they will have to take it apart to see I was $1300 which I really don’t have right now being only 17 years old. So my question is who should I believe ? should I go to another dealer? My other question is the low oil pressure stop engine light keeps coming on and flashing when I’m turning etc. when I have a good oil level So anything about that?