It is important to have your brakes checked at least once a year. Rollerbrakes are low maintenance but should be greased periodically. Disc brake pads wear out and should be replaced in a timely manner. Brake pads last about 2,000 kilometers. However, the degree of brake pad wear is highly dependent on the terrain you ride on, your braking behavior and how much mass the brakes need to bring to an halt. When a disc brake squeaks you can first clean the disc yourself with brake cleaner and a clean cloth, do this regularly. If this does not solve the squeaking, the dealer can install new brake pads.
New brake pads should always be bedded in properly. So always ask your dealer if they have done this when they replace your pads. Bedding in can also be done yourself. This is done by accelerating to maximum speed and braking (hard) to a complete stop. Repeat this 20 times in a row for new pads, then you have properly bedded in the pads.