The Financial Post reports in its Saturday edition that the big telcos spent more money to stop subscribers from leaving them last year, but one new retention tactic raised concerns among customers and lawyers alike. The Post's Emily Jackson writes that BCE and Telus reported increased wireless retention spending for both the full year and fourth quarter of 2016. It costs nearly 50 times less to keep an existing wireless customer than to acquire a new one, so it is no surprise big players are upping efforts to keep subscribers in a market where they each have about 30-per-cent market share. Bell and Telus posted an average acquisition cost of $521 compared with retention costs per subscriber of $11.04 and $11.74 respectively, CIBC's Robert Bek said in a note. While the telcos do not report retention spending numbers for their Internet and TV businesses, Bell reported "richer" acquisition and retention discounts to match competitors' deals on the wired side of the business. It is on this side of the business where the novel retention tactic raised eyebrows. Bell has started to display pop-up ads in the web browsers and on the television screens of customers who are in the process of cancelling their services.