I have received a disconnection charge from the electricity supplier, what do I do?

A termination fee is a cost that you may incur if you change electricity supplier before your contract expires. The terms of your old contract regulate the binding period, or specify a notice period, and if you terminate the contract early, you will incur a termination fee.

Do this:
Then contact your new electricity supplier and cancel the new agreement until the old agreement expires. When the agreement's binding period, or notice period, is over, you can change electricity supplier without risking any extra costs.