**TL;DR:** **Yes, you should act—otherwise, your bill will go up significantly.**

Here is the breakdown:

* **What’s happening:** Your current cheap plan ends. If you do nothing, they will automatically move you to a default variable rate that is **much more expensive** (jumping from 24.6p to 34.1p per kWh).
* **The deadline:** **28 November 2026**. 
* **What you should do:** Log into your app or online account before the deadline and choose a new fixed deal (they suggest "Fixed Saver 27"), or shop around to switch to a cheaper supplier.

*(Note: Double-check the dates—if the email actually says 2026/2027, you have plenty of time, but mark your calendar so you don't forget when the deadline hits).*