Like many of us, I changed to dual tariff pricing some while ago. However, Iberdrola have an offer for new contracts valid until the end of October with cheaper prices than I'm currently paying:
Low rate: €0.060709 per kW/h
High rate: €0.142726 per kW/h
Power charge: €42.043426 per kW/year, which works out at €0.115187 per kW/day
I printed out the PDF with the prices, plus a copy of my most recent bill, took them to the Iberdola shop in Almoradí, and asked if I could change to these prices.
They asked for my NIE number plus my passport or driving license, and five minutes later I had a new contract, with the new prices effective from tomorrow.
If you wish to do the same, the link to the PDF is: