Complex sentence: The citizens of Sofia were unable to pay the higher bills and some outright refused which in 2008 led to huge losses of the Toplofikacia company and it ran into debt with the Bulgarian energy provider Bulgargas.
Split into simpler sentences: The citizens of Sofia were unable to pay the higher bills, some outright refused. In 2008 THIS led to huge losses of the Toplofikacia company and it ran into debt with the Bulgarian energy provider Bulgargas.