Anyone ever experienced discrepancies of data between the receipt and system?

I just sent my car to Glenmarie and was told that I used semi-syn oil in my previous service as what stated in the system. This is baffling me because I'm pretty sure I asked for fully-syn before and even got the receipt of it.

This raises my suspicion. Is it possible for them to key in data differently and deliberately charge me for the service I requested but "didn't get"?

Whom should I forward this matter to?