Economy 18

I have 2 cottages with Kalirel electric radiators, entire system installed in 2009 to take advantage of Economy 18, with radiators coming on for 6 hours 3 times a day at cheap rate. It is pretty devastating to be told that the tariff is being withdrawn as without it it would seem the entire heating system is void. Is this true? Just to clarify the circumstances, the cottages are ancient, lime plastered, wattle and daub, heavily timbered, so getting hot water-pipe heating around was impossible even when doing a total refurbishment. As a retrofit it is unthinkable. I note that Bulb does offer E7 but how would that work with my set-up?