Hi all.... Need your expertise and advise...
I just had my car serviced for the 18mth/30K km last week and I didn't check what should be change from 1st service until now.... What trigger me to check is the amount I need to pay after this service but it was too late now as damage had been done.

What I want to ask are:
1) the SC change my transmission oil and injector cleaner for this 18mth service (which shd had been change during 24th after I check yesterday), when should I schedule for the next change? Shd it be at the 42mth or 48mth service?

2)how to know that the SC really did chg the transmission oil although written on the bill? Coz I found out the SC also charge me for transmission oil and injector cleaner change during my 12mth service.
Im worry that the SC charge me only without changing.

Appreciate all your help/advice and regret about my ignorance earlier due to trust the SC. 3rd mth & 6th mth service was OK.

Yup.... But too late already...damage done

That's why I need help on question 1 & 2