He told the meeting there had been small print on station banners that stated the value claim was compared to equivalent TfW tickets – but the system only measured against a full adult fare.
However, he claimed the social adverts gave no indication that tap-and-go fares were not the cheapest for everyone.
The council has now warned rail passengers to check whether a cheaper travel option is available to them before using pay-as-you-go.
Glyn Banks, cabinet member for waste and transportation, said it was a “convenient option”, but it was “important” that passengers understood it was not always the cheapest choice.
He said people could save money by buying tickets in advance, using travel passes or railcards, and that pay-as-you-go did not support railcard discounts, child, family or return tickets.
“We’ve asked TfW to make it clearer for passengers when travelling as tap and go calculates the standard adult single fare for your tapped journey,” he said.
“We hope this issue can be addressed as soon as possible to ensure passengers are not disadvantaged.”
The council’s chief executive Neil Cockerton had also written to TfW asking for new signage to be installed at stations, in order to inform passengers that they may be able to access cheaper tickets through other payment methods.
TfW said it was committed to making rail travel “as simple, convenient, and affordable as possible” for customers.
A spokesperson said: “While railcard and concessionary discounts are not yet supported via pay as you go, advice on alternative ticketing options is available on our website, at stations and through customer channels.
“We are actively reviewing how we communicate this to customers.”
TfW said it was exploring a pilot to allow eligible railcards to be linked to pay-as-you-go accounts, and hoped to introduce child fares in future, but said further development was needed.
The spokesperson said: “Free concessionary travel and family or group offers are not in scope for our pay-as-you-go offering. The latter position is aligned with that of most other pay as you go schemes nationwide.
“We remain focused on making rail travel easier, more flexible, and better value.”
The rail company said further details on improvements to its pay-as-you-go scheme would be announced in due course.