$34 for an oil change? $349 for a brake job? Both sound pricy to me.
Next time ask the manager to show you the worn parts. Far too often people are afraid to say “show me” to their mechanic before they authorize work. Be more assertive next time.
Which brake pads were replaced, the front or the rear pads? What kind of brakes are in the rear, disk brakes or drum brakes?
For the front brakes 39,000 miles sounds about right. Rear brakes should last longer since about 70% of the braking is done by the front brakes.