It's worth being prudent.A Spanish neighbour tried to change from CHC Energia to Iberdrola.All went well cancelling his contract with CHC but then Iberdrola said they would require an up to date boletin which would have meant an expensive rewire on his ageing house,and when he tried to restart his CHC contract,you can guess what happened.

We had to do that, too. But in our case, we went to a licenced electrician, who simply typed up a paper, stamped it, and charged us €300.