Complaints against two letting firms offering guaranteed rent through the agent becoming the tenant and then sub-letting the property, have both been upheld by the Advertising Standards Authority.

The upshot suggests that agents following this model will have to detail the arrangement in any advertising or other promotions.

The cases were both treated individually, but the firms, Reliance Property Management Specialists, and Smartinvest Capital trading as Victoria Knight, are in east London, and are under the same ownership.

Reliance said on its website that it offered guaranteed rent 365 days a year, guaranteeing its landlords full monthly rent payments even when the property was empty.

The complainant said that the guaranteed rent claim was misleading, because it suggested that the rent would be guaranteed in all circumstances.

The complainant also said that the advert did not make clear the significant limitations.

Reliance told the ASA that it acted as the tenant and then effectively sub-let the property.

A rent recovery insurance policy allowed the letting agent to claim for unpaid rent where the tenant had defaulted. It also provided cover for legal costs involved in pursuing a tenant.

Two landlords both told the ASA that they had continued to receive rent when their properties were vacant.

However, the ASA said that consumers would not understand from the advert that the guaranteed rent was base on Reliance becoming the tenant and then sub-letting the property.

The ASA said that this was material information likely to cause consumers to take transactional decisions they would not otherwise have taken.

There were also terms and conditions but a copy of the full terms was not available for landlords to read on the website. For example, there were limitations to the guaranteed rent for landlords if the property was uninhabitable.

In the case of Victoria Knight, its website said: “We are one of the few letting agents in the country who offer rent guarantee with professional working tenants.

“Our rent guaranteed service offers the assurance of a fixed monthly rental income without all the hassles involved in being a landlord.”

The challenge from the complainant was the same as in the Reliance case.

Again, the ASA ruled that because Victoria Knight did not make it clear that the agent became the tenant and sub-let the property, its rent guarantee claims were misleading.

Both sets of adverts have been banned.