A finance expert is urging Brits to make a note of an important date in their diary to avoid being stung by a costly £200 fee. Martin Lewis warned that this is an important step to take when trying to find the cheapest energy bills this winter.

Speaking on the latest episode of his BBC podcast, Martin advised listeners how to avoid the predicted average energy price cap increase of 10 percent, which will go up on October 1.

With this change, it is estimated that the typical annual dual-fuel…