That was a one off due to the fall in wholesale gas prices being out of step with consumer contract terms.
They've lost about a million customers over the past three years, their share price has dropped from about 300p to 90p, they've shed about 10'000 staff, Ian Conn their COE has just resigned. Doesn't sound like they lost something like £2.2bn in 2017 and £300m this year. Doesn't really sound like a business that thriving.
The cap on energy prices has really hurt them.
Google it and you will find that year on year they are making huge profits. I did put another link up but it didnt work.