Those who had invested in ING's Diversified Yield Fund (DYF) and Regular Income Fund (RIF) via ANZ had the option to file a notice seeking additional compensation before the end of July, if they considered the offer made to them by ING to be inadequate. This was despite a clause in the offer that meant investors waived taking any further action if they accepted the deal.

ING offered investors 60 cents per unit for the DYF and 62 cents for the RIF under the "cash out" option.

ANZ National managing director, private marketing and wealth, John Body, says 99% of ING investors accepted the original offer that was made.

"We received a significant number of complaints and have completed a detailed review of each case which was requested of ANZ. We have started the process of writing back to clients and where our processes have failed our customers, we will be working with them to reach a fair resolution," he says.

Agreements made between it and its customers were confidential, he adds.

Deputy banking ombudsman Susan Taylor says all of those customers have the option of going to the Banking Ombudsman if they are not satisfied with the offer received and it was currently gearing up for enquiries.

"We're expecting a lot of telephone calls, because we're expecting that people will probably call us even if they receive an offer, to say does this offer sound right? At this stage it is very hard to predict how many of those customers will come back to us," she says.

Meanwhile, the Commerce Commission is currently undertaking an investigation into the promotion, marketing and sale of the DYF/RIF funds by ING, ANZ and "other parties". A spokesperson described the investigation as ongoing. No timeframe on its completion was available.