Santander received 6% more complaints in the first half of this year than in the second half of 2016.
The bank has today published complaints data as it is required to so by the Financial Conduct Authority (FCA).
It said the 6% rise to 162,529 complaints was driven by a 25% increase in PPI-related complaints following the FCA’s announcement in March that it had set a deadline for such claims.
In the first six months of 2017, Santander had 119,221 complaints relating to banking and credit cards and 27,754 it classified as “insurance and pure protection”.
There were 10,358 complaints opened over home finance issues, 2,607 about investments and 2,517 were credit related.
The bank also dealt with 72 complaints relating to life and pensions products sold by historic group companies six or more years ago.
Santander said it had launched a number of new products and services in the past year including a mortgage video service that allows customers to apply for a loan in-branch using a video link to a mortgage advisor.
It has also introduced talking ATMs to support blind and partially sighted customers, and refurbishing 20 branches across the UK this year.
Reza Attar-Zadeh, Santander’s managing director of customer experience and complaints, said: “Helping people and businesses prosper through providing simple, personal and fair banking lies at the heart of our strategy.
“Coupled with that, aspiring to offer customers a seamless experience and excellent service is fundamental to the way we work.
“We continue to focus on how we handle complaints, and, while we know we still have more to do we remain unwavering in our commitment to deliver an exceptional customer experience.”