'Unfair' National Express Powys to London fares cut
Some passengers in mid Wales have been paying more than double the price of people getting on the same coach 60 miles earlier.
People in the Powys towns of Newtown and Welshpool have complained about the £80 fee for a return trip to London.
However, passengers boarding the coach 60 miles (95km) earlier in Aberystwyth paid just £35.
National Express said prices were based on demand but it would lower some fares.
The company's 409 service to London leaves Aberystwyth every day at 07:55 GMT and stops off at Newtown and Welshpool before arriving in the UK's capital at 15:00.
Aberystwyth is 250 miles (400km) away from the London Victoria Bus Station destination while Newtown is 200 miles (320km) away and Welshpool is 190 miles (300km).
Carole Thomas, from Trehafren, was surprised to discover she was paying more for a shorter journey if she got on at Newtown.
She told BBC Wales' X-Ray programme: "I have to go down [to London] to see my mum because she's had a stroke, she's in a home and to see my dad's grave.
"When they said it was going to be £80 I nearly fell on the floor."
Her husband Graham said it was "not fair" they had to pay more than people getting on the same coach at Aberystwyth.
Margaret Thomas, who boards in Welshpool, said: "They said it's the volume of people going on in Welshpool and Newtown... Maybe just one person.
"But the bus is already coming from Aberystwyth. I just don't understand."
National Express's conditions forbid passengers buying the cheaper Aberystwyth to London ticket and getting on at a later stop.
Prof Stuart Cole, a transport expert at the University of South Wales, said while passengers might think the pricing policy was unfair, the company needed to make a profit.
"Aberystwyth is a student market in the main," he said.
"It's a very big market, a very important market and the company wouldn't want to lose it to the competition which is there from other coach companies and also from the railways."
X-Ray also found a return ticket from Newport to Liverpool for £42 - but getting on the same bus 13 miles earlier at Cardiff would cost £6 less.
National Express said it set ticket prices according to demand - not mileage or the time of day - to make best use of the capacity on its coaches and keep its prices competitive.
But the firm has now reduced its "lowest available fare" from Newtown to London to match the price from Aberystwyth, but is not cutting fares from Welshpool.
It also lowered the price of tickets from Newport to Liverpool.
X-Ray is on BBC One Wales at 19:30 on Friday, 17 March and is also available on BBC iPlayer.