Customer satisfaction levels fell last year for the first time in four years after peaking in 2014.
Results released by the Institute of Service Excellence (ISES) at the Singapore Management University yesterday showed that the overall score dipped from 71.1 out of 100 in 2014 to 70.2 last year.
This was due in part to poorer performances by the finance and insurance and healthcare sectors.
While the study did not capture complaint types, a common observation from companies in the finance and insurance sector was lower customer satisfaction with touch points such as bank branches, personal bankers and financial advisers.
The life insurance sub-sector saw the biggest fall, with a decline of 4.1 per cent, followed by health and medical insurance, which dropped 3 per cent.
The bank sub-sector dropped 1.6 per cent, and the motor and other personal insurance sub-sector fell 1.4 per cent.
Maybank, which leapt from seventh place to first for bank customer satisfaction, attributed its improvement to a reduction in waiting times, among other initiatives.
The decline in the healthcare sector's score came primarily from decreased satisfaction with general practitioners and the "other healthcare" sub-sector, which comprises specialist providers, dental and traditional Chinese medicine clinics.
The private education sector fell 2.5 per cent, while the info-communications, retail and tourism sectors did not register substantial changes, the ISES added.
The food and beverage and public education sectors, however, registered gains of 2 per cent and 1.6 per cent respectively.
The air transport, land transport and logistics sectors, previously lumped into a single category, were introduced last year and do not have a benchmark comparison.
The 2015 study polled 42,501 local residents and departing tourists and covered 2,330 companies in the 11 measured industry sectors.
Professor Jochen Wirtz of the National University of Singapore Business School said: "Customers are getting very impatient when things are not seamless or require several interactions.
"Especially for banking and insurance, more is done now online and on apps. When you call your bank, there's usually a problem, so a lot rests on how good they are at dealing with service issues."