In article .com,
John B wrote:
Single z3-z6 costs £1.80 on-peak or £1 off-peak.
Single z3 only costs £1 at all times.
Single z6-z3 via z1 costs £3.50 on-peak or £2 off-peak.

So off-peak the passenger would be charged £2, irrespective of how the
fare is calculated.

On-peak, the passenger would be charged £2.80 for 2 journeys plus
travelcard, or £3.50 for one journey.

Surely the passenger would be charged 1.80 or 1 for a z3-6 extension,
given that it is a single journey that needs z1-6 validity?

The travelcard part provides the z12 validty, the extension provides
z3-6 for a single journey.

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I don't play The Game - it's for five-year-olds with delusions of adulthood.