Unresolved complaints about the mis-selling of payment protection insurance (PPI) still dominate the in-tray of the Financial Ombudsman Service.
The body received 150,000 new complaints in total in the six months to last December.
Just over half of them - 78,000 - were about PPI policies, the sale of which has been largely banned for some time.
The ombudsman deals with complaints which financial firms have been unable to settle themselves.
Caroline Wayman, who heads up the body, said: "PPI complaints are down, but there are some suggestions that this could be the calm before the storm."
A deadline of June 2019 could be set by the Financial Conduct Authority (FCA) for disgruntled customers to make compensation claims to their banks and credit card issuers about mis-sold PPI policies.
The FCA wants to decide on the deadline in the middle of this year along with a public awareness campaign.
"The FCA's proposals - including the PPI deadline - are likely to heavily influence our complaints volumes," Ms Wayman said.
Millions of people have already been paid compensation following what was one of the banking industry's biggest scandals.
More than £40bn has already been set aside by banks to cover the payouts and the associated overhead costs of processing claims, and it is widely suspected that many more complainants could come forward.
The compensation process has not been smooth for customers though.
Since 2003 about one and a half million people have been so dissatisfied with the PPI offers that were made to them, or the outright rejection of their claims, that they have subsequently gone to the financial ombudsman.
In the second half of 2016, nearly half of the PPI complaints to the ombudsman were upheld against the top ten most-complained about businesses.
However, the uphold rate varied wildly between providers, from 9% for Nationwide to 29% for Bank of Scotland and 69% for Financial Insurance Company Ltd, part of the AXA group.
The list of most-complained about businesses - for all types of complaint to the financial ombudsman - is still dominated by the UK's High Street banks, and some credit card lenders.
Top of the list in the last half of 2016 was the Bank of Scotland, which is part of the Lloyds banking group, with nearly 20,000 new complaints against it.
It was followed by Lloyds bank itself, Barclays, HSBC, NatWest, the credit card firms Capital One and MBNA, Santander and the Nationwide building society.