The cost of getting a First Bus in Bristol is set to rise this weekend.
Fares will rise by an average of about 3%, adding up to 10p on the cost of a ticket, the company said.
Kerry McCarthy, Labour MP for Bristol East, said previous fare rises had resulted in no improvements and buses were still "unreliable".
First Bus said the redevelopment of the Broadmead shopping centre had resulted in increased congestion and a subsequent rise in costs.
The company's Simon Cursio said: "It has been over a year since the last review of our fares and we are pleased to have kept the increase so low."
Ms McCarthy said: "Bus passengers in Bristol will quite rightly ask whether they are getting value for their money, as First introduces yet another fare rise.
"People might be prepared to pay more if they were getting a decent bus service but previous fare increases have resulted in no improvement.
"Bristol's buses are still unreliable as well as being far more expensive than in many comparable cities.
"It's not good enough for First Group to blame it on congestion. If there was an affordable and reliable bus service, more people would choose to take the bus and we wouldn't have so many cars clogging up the roads."
First Bus also said some fares would be reduced as part of the review, but FirstTen will rise from £20 to £24.