Brake pads and discs wear gradually. Most cars give plenty of signs that something needs attention, if you know what to listen and feel for.
Squealing or grinding
A high-pitched squeal can mean pads are nearing the end of their life. Grinding often means they are worn through, which damages the discs quickly.
A soft or sinking pedal
A spongy pedal or one that sinks towards the floor can point to air or a leak in the hydraulic system. Have it checked before driving further.
Pulling or vibration
If the car pulls to one side when braking, or the steering wheel shakes, ask a garage to check the calipers and discs.
Warning lights
A brake or ABS warning light should never be ignored. Stop somewhere safe and get advice.
Ask what was replaced
After a brake repair, ask the garage which parts were replaced and to show you the old ones.