British sales of frozen beef burgers collapsed by 43 percent and ready meals by 13 percent in the wake of the horsemeat scandal, data showed Tuesday from retail consultancy Kantar Worldpanel. However, many Britons have changed the products they buy rather than where they shop, according to Kantar. "The issue has so far only affected the performance of individual markets rather than where consumers are choosing to shop," said Kantar Worldpanel director Edward Garner.