Usdaw wants chains to follow Sainsbury's and Waterstones and end long-term unpaid labour for young unemployedUnions have called on Britain's biggest high street chains to withdraw from government programmes that make the unemployed work for up to six months unpaid or face losing their benefits.The call comes as Sainsbury's, one of the UK's largest retailers, confirmed to the Guardian that it has stopped branch managers from taking on jobseekers under the work experience scheme.The move follows that of Waterstones book chain, which last week announced it had pulled out of the scheme because it did not want to "encourage work for no pay".Under the work experience scheme, hundreds of thousands of largely young jobseekers will work in charities and private ...