Nationwide has been named the UK's best-performing brand for customer service, as banks and building societies overtook retailers for the first time, reflecting a dramatic turnaround for a sector still rebuilding trust after the 2008 financial crisis.The latest UK Customer Satisfaction Index (UKCSI), published by the Institute of Customer Service, gave Nationwide a score of 87.3 out of 100, ahead of John Lewis on 87.1 and digital bank First Direct on 86.0. Jet2holidays, Specsavers and PayPal also scored well.The survey found customer satisfaction has now improved for a fourth consecutive reporting period, rising by one point over the past year to 78.3.However, the pace of improvement has slowed sharply, with the index increasing by just 0.1 points over the past six months as consumers beco