Average if of unique values with conditions

Hi all,

I have a table of rail fares for a set of Origin-Destinations. At a high-level, each fare is either an Advance ticket or a Single ticket (but a lot of fares have restrictions on the train operators you can use, so some Advance tickets for a given origin-destination at a given fare price may appear more than once, creating effectively duplicate entries). A given Origin-Destination could also have several different Advance ticket prices (as prices for a train ticket can change as the day of travel approaches).

I'm after a formula which computes an average fare for each unique Origin-Destination and ticket type (eg. average Advance fare to travel from London Euston to Manchester), but I want to omit duplicates (identical Origin-Destination, ticket type, and fare price) from the calculation.

Any help would be greatly appreciated, thanks.

Example with expected answers provided - red text cells are the example of duplicate, identical fares.