All cars and vans should be service in accordance with the manufactures schedule to ensure that components are checked and replaced when needed. All service schedules can vary from vehicle to vehicle so it is advised to check what is required for your specific make and model of car.
There is often a huge price difference between getting your vehicle serviced at a main dealer garage as opposed to another independent garage. Some cars that are under a warranty must be serviced at a main dealer to ensure that the warranty is not invalidated.
If you do use an independent garage, then check what parts they are using when replacing them. It may be that they are going to use non genuine parts, which may be ok as long as you are aware of it. It is often worth getting a price for a service using non genuine parts and genuine to see what the price difference is.
Throughout the life of a car there are different types of services often called minor services and major. Major services often cost a lot more but sometimes include major component changes such as cam belts etc.