Barclays said customer complaints fell by a quarter in the first six months of 2014, as cases of mis-sold loan insurance declined.The bank has a worldwide customer base of 48m and it received 284,000 complaints in the first half of 2014, a 26% decrease year-on-year.Complaints about insurance, the majority of which are directly related to payment protection insurance (PPI) sold in Britain fell to 183,000, Barclays said, a 37% decline from the same period in 2014.PPI have proved to be extremely expensive for British banks, with over £22bn set aside so far to compensate disgruntled customers.Barclays shares were down 0.04% to 223.95p at 14:34 on Friday.DC