I think in general, you got to be knowledgeable on what neds to be changed during each servicing.
Motor workshops are commercial entities whereby their primary objective is to generate profit.
My friend (not knowledgeable about cars)) sent his Vios to Motogard at Tampines, after seeing their cheap synthetioc oil costing below $100.
In the end, he got charged for a lot of "extras" including adjustng/tightening the handbrake.
They also called him to say that his 4 tyres had uneven wear and advised him to change them. The tyres were changed just a yr ago and travelled only 20,000km. I suspect Motogard sold his used tyres and they deal in used tyres too.
They also recommended that he change to broader 195/60R14 tyres (stock size is 185/65R14) "for better grip". These Goodyear NCT5 tyres cost more than the stock tyre size.
He got a shock when he got the bill, and said he should have just sent it to Borneo Motors.
Penny wise, pound foolish.