Bank customers are increasingly unhappy with the way their complaints are handled by staff.
Transactions concerning mortgages were the biggest bone of contention among the public, who complained to the Financial Services Ombudsman.
And household insurance complaints and pensions were also near the top of the list of gripes from dissatisfied customers. Some 1,900 were unhappy with insurance products they had purchased.
Ombudsman Bill Prasifka revealed that banks and other financial institutions are getting worse at dealing with complaints from the public.
His actions led to pay-outs by institutions to their customers of almost €790,000 in six months.
The State's financial services watchdog declared his investigations into an increased number of complaints was a matter of "serious concern" as he handled 3,700 complaints in just six months.
Mr Prasifka said financial institutions are still not dealing quickly enough with people who make complaints.
"Trends indicate deterioration in complaint handling by financial institutions, and increased dissatisfaction by consumers across a number of areas," he warned.
Launching his report for the first half of this year, he said he expected more complaints to be received in the second half.
There was a near doubling of complaints about payment protection in the first six months of this year. Some of these complaints were due to the continuing financial pressures on people in difficult economic times. Increased media reporting on the issue also raised awareness among customers.
One in four complaints were upheld by the Ombudsman.