Premium rate services regulator PhonepayPlus has released data that shows that 15% of adults who have made a small digital payment have been billed more than expected or encountered another sort of problem.
The survey of 4,000 people showed that 55% had made a digital payment of up to £10 ($16.4) in the last six months, including via mobile and tablets.
15% of these had encountered problems including issues such as being billed for a game that they thought was free, signing up for a subscription when they thought it was a one-off payment or unwittingly agreeing to receive marketing information.
Nearly half of these people had not complained and absorbed the extra costs themselves.
Patrick Guthrie, PhonepayPlus’ director of strategy and communications, said: " Over time, small losses mount up for each consumer, and across the whole digital payments market these small amounts pile up very quickly.
"With the market for digital payments, goods and services growing rapidly, the issue of consumer confidence and redress is an increasingly important one."
The regulator is advising consumers to check their bill and follow up anything that does not look right with their phone operator, the company that charged them, or PhonepayPlus.