The Consumer Council on Thursday called for more transparency from residential property developers on owners' rights and management fees, following a two-year study sparked by hundreds of complaints over the past decade or so.

The council conceded that it struggles to resolve a lot of complaints about property management charges or service quality, due to the complexity of the issues involved.

Its study found that most flat owners don't understand how management shares are allocated, and therefore how much of a building's running costs will fall to them, and said this hampers their ability to make informed decisions when buying a place.

The council also warned that in some cases, flat owners may not have enough of a building's ownership shares between them to pass resolutions on management decisions, and a party holding a greater amount can then control management of the property – including which company runs things.

The watchdog said it examined the situation at 249 development projects and found that at five of them, the residents held less than 50 percent of the ownership shares between them.

At 75 percent of the development projects, the management firms involved had links to the developers, the council added.

The watchdog warned that such arrangements are a potential conflict of interest.

Antonio Kwong, who chairs the council's trade practices and consumer complaints review committee, said developers should disclose clear calculations and allocations of management shares in brochures for first-hand flat sales.

He also said it would be a good idea for a database to be set up with collated information on the level of management fees charged across the city, so flat owners could get a better idea of what they should be paying.

"Obviously we need to draw comparisons based on building age, the locality of the building, the facilities being provided so that owners can make an informed choice," he said.

Kwong further suggested that property management companies should make more use of apps or social media to communicate with flat owners, and that residents should also try to get more involved in property management issues.

"What we found out is that it seems like a lot of owners are unwilling to participate in the owner’s committee, and also for example like decision making, attending the meetings, and also making the voting on certain issues," he said.

“Now from our study, it seems like when owners have a high level of involvement in property management, and also when they have an influence on the property management companies, it reflected on a lower property fee increment.”