Whoop Energy and XCel Power have ceased trading - affecting around 550 customers. Consumers from both energy firms will be designated a new supplier by market regulator Ofgem - through its supplier of last resort process. Whoop Energy (Whoop) provides gas and electricity to 262 customers, including 50 households (domestic consumers). XCel Power (XCel) is a gas only service, that is responsible for 274 non-domestic customer accounts. Neil Lawrence, director of retail at Ofgem, said: "Ofgem's number one priority is to protect...