Barclays received the most complaints of all banks in the first half of 2011, with 251,563 new complaints.
The FSA’s complaints data, published today, shows Lloyds was second with 181,907, followed by Santander with 168,888 and NatWest with 147,109.
Barclays upheld 53 per cent of complaints during the period, while Lloyds upheld 58 per cent, Santander 49 per cent and NatWest 69 per cent.
The FSA data includes firms that report 500 or more complaints in a six-monthly reporting period.
Sesame, which is the only IFA network included in the list, received 958 complaints during H1 and upheld 23 per cent.