Steve,
If it was me, I would cancel your DD with Scotish Power, as they have accepted they do not supply your electricty (but get it in writing, and document everything) get the fault fixed by a local sparky and keep the bill in readiness to charge SP.
Set up a DD into a seperate account for slightly more than you estimate you would owe.
Sit back and see what happens
Someone must be responsible for your leccy supply, but have not realised they need to bill you.
In the 80's a mate of mine bought a hotel/guest house in Llandudno which had gas central heating and gas powered kitchen ovens, all supplied by British Gas.
Despite several letters, phone calls etc. British Gas insisted the hotel had no gas connection or gas supply, and they had no record of his property.
I think this was still the case 11 years later when my mate sold up and retired. He did admit he had a knee trembler about six years in, when British Gas repaired a reported gas leak at the bottom of their driveway.
No idea what happend to the money deposited in his seperate gas bill account