I just found a referral code on here after deciding to switch this morning to someone who is less ridiculous when it comes to setting direct debit prices (hello EON.Next) - it gave me £50 off my energy and £50 for them as well when the switch happens.
I'll paste my similar code below if anyone else wants to do the same
https://share.octopus.energy/bold-cub-608
Even if your switch is already in progress (as mine was) you can go in and apply this retrospectively... which is even better! I hope it helps someone.