A 'DISTURBING' number of High Notes 5 investors have yet to receive any reply from DBS Bank after filing complaints that they were mis-sold the notes, said Mr Gerard Ee on Tuesday.

This is despite the Monetary Authority of Singapore (MAS) advising financial institutions to respond promptly to complaints from angry customers who had bought the Lehman Brothers-linked structured products.

Among other things, institutions who sold products such as DBS's High Notes 5, Lehman Minibonds and Merrill Lynch Jubilee Series 3 are advised to acknowledge receipt of a complaint within two working days.

But some investors are griping that DBS has taken 'weeks' to respond to their complaints, said Mr Ee, who was appointed by DBS as an independent external consultant to oversee its process of handling customer complaints.

'I accept there will be lapses because of the volume itself, you can't process hundreds of cases within 48 hours,' Mr Ee told reporters on the sidelines of two High Notes investor forums held at Suntec City on Tuesday.

'But to hear people saying that it's been three weeks, four weeks, five weeks and they haven't heard a reply, that's not acceptable.'

'Especially during this period where people are emotional, they want a reply... if nothing more, just to acknowledge that I've received your complaint and I'm attending to it,' said Mr Ee. 'But total silence is not acceptable.'

In response to his remarks, a DBS spokesperson on Tuesday apologised for the bank being unable to contact all its investors immediately due to the overwhelming number of cases.

'We acknowledge and apologise that due to the sheer volume on hand, we were not able to contact a number of our investors and are doing our best to expedite the review of all cases as soon as we can,' the spokesperson said.

To date, DBS has received more than 650 complaints from its High Notes 5 investors, added the spokesperson. The bank has contacted 85 per cent of these customers, 'informing them that we have received their feedback and are in the midst of investigating their cases'.

DBS also said it is exploring ways to improve its complaint handling process as it has committed to review all 1,400 High Notes 5 cases by the end of the year.