The Financial Services Ombudsman said his office received more complaints in March 2011 than in any month since its establishment.
Complaints about investment and insurance products remained at record highs during the last six months of 2010 and there was a 40% increase in mortgage-related complaints.
Almost half of the complaints received by the office overall related to the insurance sector and complaints about household insurance policies in 2010 doubled because of flooding and severe winter weather.
Ombudsman Bill Prasifka, investigates complaints against banks and financial institutions by consumers and he says his office can barely cope with the weight of complaints.
The review shows that a total of 3,599 complaints were received in the last six months of last year, compared to 3,631 in the first six months of the year.
Banks came next, at 33% of complaints received, followed by complaints about investment firms.
Compensation of over €1.3m was awarded to financial institutions' customers, compared to €1.29m in the first half of the year.
The Ombudsman said that 15,000 phone call queries were received, while over 37,500 website hits were recorded.
'The large increase in complaints in certain areas reflects the immense difficulties facing consumers and the financial industry as a whole,' commented Mr Prasifka.
'The fact that over €2.6m was awarded in compensation by the Office in 2010 shows that some financial institutions are still not making efforts to resolve complaints sooner,' he said.
He said that he is even more concerned about the substantial increase in the number of complaints received by the office in 2011. 'Much more needs to be done to begin to restore public confidence to the financial sector,' he added.
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