British Telecom in the UK is likely to get a bill shortly from Sky for rather a lot of money, reclaiming overcharges on maintenance costs for its broadband lines. This conclusion is hidden in a 90 page Ofcom document which goes into just how it investigated the charging mechanisms of BT, and how it calculates just what re-charge levels are allowed. The practice has been going on since 2009, and Sky has some 5.3 million broadband lines. They fall into two categories, fully unbundled lines and wholesaled, with most of its original broadband lines being ULL, but more recently Sky signing up more wholesale. This is partly because vectored VDSL lines which offer service up to 100 Mbps, need a…