Jim
It helps to know the model. Your profile shows a 123 chassis, no A service on that one!
Most A services are mostly an oil and filter change, inspections of various systems, and depending on age, possibly a brake fluid and coolant flush.
It MAY involve more work if for example your brakes are worn out, but you'd need to authorize the extra work.
What year/model do you have, and how many miles?

Gilly