'Surprise' or 'drip-fed' charges made by letting agents are commonplace, according to a report by the Office of Fair Trading (OFT) published today.
The report identified poor service and delayed or substandard repairs as other sources of friction between letting agents and landlords and tenants. The OFT's findings are the product of analysing nearly 4,000 complaints about the lettings industry made to Consumer Direct in 2011.
More than 1,550 of those related to fees and charges, which the OFT said were either "surprise" or "drip-fed" once contracts have been signed.
Next on the list was agents providing poor service, while more than 500 complaints targeted unfair business practices.
Cavendish Elithorn, senior director of goods and consumer at the OFT, says: "Our findings show that tenants and landlords are often dissatisfied with their agents but we also know that most agents want to do the right thing.
"It's important that tenants ask for key information, but we also believe the government, industry and enforcers working together can have a real impact and improve overall standards in the lettings market."
The OFT's report recommended fees and charges be set out in a clear tariff, that there is more consistency in the industry and educational guides are produced to help tenants and landlords understand their rights.
Scott Hammond, executive director of Essential Living, a developer focused on private-sector rented housing, says: "One of the causes of rental horror stories is the fragmented nature of the buy-to-let market. Individual landlords and agents can easily get away with flouting the rules and this is why so many people have problems renting a home."
He says more controls would "help housing shake off its murky reputation and build new confidence from consumers".