Energy watchdog Ofgem has found that 18 gas and electricity suppliers overcharged customers when they switched to better deals.

Here is the list of suppliers and compensation bills:

Supplier, Number of customers affected, Total redress

Bristol Energy 12,617 £56,552.64
British Gas 141,415 £1,269,095.47
E 20,870 £72,772.93
E.On 28,126 £238,884.29
EDF 79,083 £516,191.55
Engie 9,061 £21,218.74
ESB Energy 1,961 £49,787.00
Green Star 79,083 £808,351.00
Energy npower 2,030 £25,602.69
Octopus Energy 19,712 £121,444.52
Orbit 723 £7,081.12
OVO Energy 240,563 £2,801,231.51
PFP Energy 5,347 £50,929.31
Scottish Power 157,236 £1,967,465.28
Shell 225,823 £1,217,203.40
So Energy 10,514 £78,480.89
SSE 132,620 £983,334.45
Utility Warehouse 2,723 £95,512.15