Credit from old supplier

I was with Iresa and had a D/D with them.
They went bust and Octopus took over. I didn’t set up a D/D with them as they had access to the Iresa D/D and used it to continue taking payments.
As soon as possible I moved to Bulb and have begun making payments to them via D/D.
Octopus tell me I have a £90 credit from Iresa.
Octopus tell me that in order to get my refund I have to cancel my D/D with Iresa and set one up with Octopus.
But I’m not with Octopus, I’m with Bulb.
Why would I set up a D/D with a company I’m not with and never signed up to?
I’m confused.

I’m purely another Bulb Customer but my understanding is that when Iresa went bust you were automatically transferred to Octopus on a deemed contract which is part of the safety procedures introduced by OFGEM when a company goes bust.

So by default you were a customer of Octopus. I would suggest you contact them to advise you have switched to Bulb. I assume that they have asked you to set up a new DD with them so that they have an avenue to refund any credit.

There is a lot of information on this OFGEM page: