OTTAWA—A public-opinion poll conducted in September for Canada’s national telecommunications regulator found that 21 per cent of the respondents had experienced “bill shock” from their wireless services.

The most recent survey by TNS Canada for the CRTC showed a statistically meaningful decline in complaints about bill shock since a survey done in 2014, when 28 per cent of respondents had experienced the problem.

But the TNS Canada analysis said there was “room for improvement” since Canadians continue to struggle with tracking how much data and calling minutes they have used. Managing the cost of international roaming fees is another problematic issue.

The survey was done in preparation for a public hearing that the Canadian Radio-television and Telecommunications Commission will hold from Feb. 6-14 as part of its review of a 2013 code of conduct for wireless service providers.

The poll was based on a telephone survey of 1,483 people aged 18 years and older, conducted from Sept. 6 to 19 — making it accurate within 2.5 percentage points, 19 times out of 20.