Vacuum hoses and Saab

I have a 2000 Saab 9-5 Wagon. Recently, it went in for its 90,000 routine maintenance. This included inspection of Vacuum hoses/lines (?I’m not very car literate). Soon after I had the car back, I noticed the brakes seemed faulty. Over the next few weeks, it reached a point where I had to jam the brake pedal to the floor even to slow the car as I was backing out of the garage. My braking reached a point of being unsafe.

So…I took the car back in to the dealer (now about 4 weeks after maintenance). Late that day, received a call that there was a problem with the vacuum hoses and oil was being pulled into the brake line and there was no longer any brake fluid. Hence, I was was trying to apply brakes using oil instead of brake fluid in the brake line. The fix was quote at approx. $1700. Does this make any sense to anyone? How does this happen? I also just don’t think it is worth spending $1700 to fix this problem. Any insight appreciated. Thanks so much

Things really need to be clarified as oil cannot get into the brake fluid unless it was put there by someone.

If there really is oil in the brake fluid resevoir then yes, this will kill the brake hydraulics. (master cylinder, calipers, etc. etc)

Who performed this service? Dealer, independent shop, etc.

Any charges on there for a brake fluid change or flush?

Thanks so much
I will check on brake fluid change or flush
and yes, service was provided by dealer. All work on this Saab has been
performed by original dealer.