Myki refunds are so confusing to customers that the ombudsman will step in to investigate how they are calculated.

The issue has become one of the biggest sources of public transport complaints.

Travellers made 1381 complaints to the Public Transport Ombudsman about myki tickets in 2018, up from 990 in 2017.

Myki refunds are one of the biggest sources of complaints on the public transport system. Credit:John Woudstra

Refunds were the main source of frustration, followed by problems with topping up myki cards and concerns about myki charges.