One of the more obvious ways that costs can be charged, Ms Bernasconi said, is by offering clients a very low cash rate.

“When interest rates were higher this was even worse, but it’s clear from a lot of the ASX-listed platforms that are focused to disclose where they generate their revenue from, that most of their margins have been made off clients’ cash,” she said.

Some providers have lowered their cash rate for clients further, she said, after coming under pressure from shareholders about their share price.

“They think, ‘Well, we need to make some more money, we’ll just lower the cash rate that’s offered to clients and keep more for ourselves’. That’s leverage that will become less and less powerful as the cash rate continues to fall,” she explained.

“Some of the platforms only give 0.5 [of a percentage point]; it may even be lower now after the cash rate was cut.”

Another area where hidden fees can arise, she warned, is with some of the wholesale products offered by the larger platform providers.

“This is one of the oldest ways of making money. So, you negotiate with fund managers on the managed expense ratio and indirect costs of the fund and then you increase it and then keep the difference. Some of these products will advertise as having no administration fee, but if you do the maths, it’s a lot more expensive than if you got that asset structure off the shelf,” she explained.

“As soon as you become a product, you can do a lot that’s hidden, so there’s an opaqueness which means you can do a lot more hiding behind the scenes. When you don’t have that product wrapper, ultimately i’ts all transparent, you can see all the assets and every dollar that goes to the buyer’s bank account.”