Barclays bank has been named as the Financial Conduct Authority's (FCA's) most complained about firm for the second half of last year.
The figures show that there were 3,422,384 complaints in the period, an increase of 1% on the first half of 2012.
The top five most complained about financial firms, in terms of the number of complaints opened in the second half of 2012, are:
1. Barclays bank - 414,302 (a decrease of 6% since the first half of 2012)
2. Lloyds TSB bank - 349,386 (a decrease of 19% since the first half of 2012)
3. Bank of Scotland - 338,912 (a decrease of 7% since the first half of 2012)
4. MBNA - 270,486 (a decrease of 3% since the first half of 2012)
5. Santander UK - 237,923 (a decrease of 1% since the first half of 2012)
Santander UK topped the list of most complained about in the banking sector, attracting 125,451 complaints during the period.
It was followed closely by Barclays, which attracted 118,031 banking complaints.
Santander and Barclays also jostled for the top most complained about in the investments sector, with Santander attracting 2,236 just above Barclays with 2,151.
For the decumulation, life and pensions sector the Prudential Assurance Company Limited was the most complained about, with 7,788.
It was followed by Aviva with 6,554 complaints.
The top five most complained about financial products, in terms of number of complaints opened in the second half of 2012, are:
1. Payment protection insurance (PPI) - 2,170,537 (a 5% increase on the first half of 2012)
2. Current accounts - 304,196 (a 6% decrease on the first half of 2012)
3. Other general insurance products (excluding PPI) such as travel, motor or critical illness insurance - 296,679 (a 6% increase on the first half of 2012)
4. Credit cards - 283,705 (a 14% decrease on the first half of 2012)
5. Savings (including cash ISAs) and other banking products - 100,797 (a 20% decrease on the first half of 2012)
Complaints for all types of financial products decreased in the second half of 2012 with the exception of general insurance and pure protection products - which includes PPI - which increased by 5% to 2,494,247.
PPI complaints alone rose by 5% to 2,170,537 and accounted for 63% of all complaints.
The total amount of redress paid in the second half of 2012 was £2.95bn, a decrease from £3.17bn in the first half of the year.
Martin Wheatley, FCA chief executive, said:"Greater transparency drives greater competition, and the publication of the complaints data lays bare the track record of the UK's financial institutions when it comes to resolving customer conflicts.
"When I meet with the bosses of the financial institutions they frequently tell me that they don't want to be at the top of the table, which means they strive to improve both their sales and complaints handling processes.
"Not only does our data help consumers compare and contrast their current bank or lender, but it also boosts competition among firms too."
The FCA requires firms with more than 500 complaints opened in a reporting period to publish this data on their websites.
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