article_snippet: The number of customers trapped in poor-paying ISAs has doubled in the last two years .
article_snippet: The number of customers trapped in poor-paying ISAs poor-paying ISAs has doubled in the last two years as interest rates on customers trapped in poor-paying Isas plummet to new lows.
article_snippet: The proportion of these tax-free accounts returning below 1 per cent has doubled in the last two years, from one in six to one in three.
highlights_snippet: Number of tax-free accounts returning less than 1% has doubled .