Yes they can, normally if a company aquires a business they will transfer all of the contracts, as part of the agreement, and the supply just continues as normal, for example in the Murcia area wher I am the same thing happened with gas and all that changed was the name of the top of the bill
They don't have to ask for permission form the consumers to sell their business or even get new contracts signed, especially if the terms do not change
I would expcet that the supply terms will remain the same
What isn't acceptable is as stated that you are not receiving bills, but again this is very normal in Spain which is why the administrators need to actually visit the suppliers offices to resolve this matter
Chances are they will will also make a charge to re-connect the power