@
Timscotland
Since you left Symbio well before the Company went under I fear you might be treated are a creditor of the failed company and, if so, likely to get little from the liquidator. Its not clear if there is a time cut off for customer balances for customers who left Symbio before the collapse.
I've looked at the OFGEM website and its very unclear what happens in these situations. Given that Eon Next is now the "supplier of Last resort" for customers who were still with Symbio when it went under, you will have to start with their customer services (as you probably already have). I presume you actual supply is not with Eon next.
Peter above says that your credit is protected, but clearly something is wrong because you don't have your money back. It will have been for the Administrators of Symbio to notify Eon next of the appropriate balances. Its also possible that because you will not necessarily have set up an account with Eon Next, they've done little to get your money back to you.
Eon next don't bear the cost of refunds in these situations as the credit balances paid out by them are recovered from some sort of central fund, which then collects the cash back from all customers with an electricity account via their standing charge.
I would suggest doing as Peter above suggests giving as much detail as possible.
give them a couple of weeks and then be ready to make a formal complaint. This isn't a normal situation but Eon Next should be able to sort it within 2 weeks.
Yours isn't the first non payment of Symbio credit notified to the forum, but the other person had multiple accounts and might have been treated as a trader/business and thus not eligible for the credit.