There's a few ways that you can contact your supplier, or a prospective future supplier you're looking to switch to, but the quickest way is by phone. Below you'll find a list of all of the current suppliers on the market, along with their phone number*.
British Gas/Scottish Gas: 0330 808 3880
Co-operative Energy: 0808 164 1088
E: 0333 103 9575
E.on Next: 0808 501 5200
Ecotricity: 0345 5557 100
EDF Energy: 0333 006 9950
Good Energy: 0345 034 2404
100Green (previously Green Energy UK): 0192 048 6156
Octopus Energy: 0808 164 1088
Outfox the Market: 0800 103 2702
Ovo/Boost Energy: 0330 175 9669 (prepayment) or 0330 303 5063 (pay monthly)
Sainsbury's Energy: 0808 501 5277
Scottish Power: 0345 270 0700
So Energy: 0330 111 5050
Utilita: 0330 333 7442
Utility Warehouse: 0333 777 0777
*Phone numbers and suppliers correct at the time of this support article being written.