Phones 4U, the British phone retailer which is controlled by BC Partners, the private equity group, stands to lose a major part of its sales after UK mobile phone operator Vodafone revealed it would withdraw its products from the chain next year. The value of debt in Phones 4U, listed on the Irish stock exchange, fell by about three-quarters on Monday after the announcement. The decision will leave the retailer with only EE as a full mobile network operator partner, although the future of that contract is also in question given a review taking place at the telecoms group.