Dishonesty

So last year on the 16th December i took my car for a service at Nissan North west in westgate,then i was told that i need to change my brake pads as they are finished i agreed to that and paid. To my surprise this year before the 16 of Jan my brakes were making sounds to show they need to be renewed. Went back to them then i was told to pay R800 for them to check. I didn't know that I'd be ****med by such a big dealer. How do i pay 800 after paying so much money at first what guarantee do i have that they will do the right job this time? And guess what they gave me everything that was changed in the car including the old oil but the were no brake pads in ther i chose not to ask cos i thought they are reliable but i regret ever setting my foot there.