How do I get my money back from previous energy supplier?

Loonytunes wrote: »

I made a complaint in April, which they didn't reply to so have today taken it to the ombudsman. Thanks everyone for your help.

Did you follow both steps?
If not I suggest you do step 2 today!

kapum wrote: »

Actually it is. Your error in thinking black is white. :cool:
You're not the first on this forum, and I feel sure you won't be the last.

That's an interesting comment from someone who registered their forum account just last month and has only made a handful of posts. It's almost as if you had another account prior to this, perhaps PPR'd. It wouldn't surprise me. Anyway, if it pleases you to think that, go right ahead. I'm happy for other readers to reach their own conclusion.

... followed the complaint process IN FULL

How very drole. In case this point has not been sufficiently debunked already, here's what Ombudsman Services, OFGEM and Citizen's Advice have to say on the matter:

"How long do I have to wait before I can log a complaint about my provider?
Your provider has six to eight weeks - depending on which one you use - to resolve your complaint. This is to give them enough time to assess the situation and the evidence to find an appropriate resolution...

What if my provider wants more than eight weeks to resolve my complaint?
It's up to you if you would like to refer your complaint to us. You can choose to wait and see if your provider resolves your issues with more time, or you can still raise a complaint with us. As long as your complaint is eight weeks old, the provider can't stop you from escalating your complaint."
https://www.ombudsman-services.org/FAQs/using-our-service#how-long-do-i-have-to-wait-before-i-can-log-a-complaint-about-my-provider

"Taking it further
Ombudsman Services Energy can investigate if: the complaint hasn’t been resolved to your satisfaction after 8 weeks; or the energy company deadlocks the complaint (they say they can do no more to resolve it) before 8 weeks are up"
https://www.ofgem.gov.uk/consumers/business-gas-and-electricity-guide/complain-about-your-gas-or-electricity-bill-or-supplier

"You can complain to the energy ombudsman if you’ve already complained to your energy company and either:
- you’re not happy with their decision
- you’ve not been given a decision within 8 weeks"
https://www.citizensadvice.org.uk/consumer/energy/energy-supply/complain-about-an-energy-company/complain-to-the-energy-ombudsman/

If this conflicts with your experience of complaining to the Ombudsman, then either there is more the decision not to investigate than you have shared with us, or you have grounds for complaint about the service you received from the Ombudsman.