I left SSE in December 2020.
They continued to take payment for gas until March 2021 when I cancelled the direct debit.
Initially they were very helpful and explained there had been a mix up but it was going to be resolved in the next few weeks.
It is now December 2021 and I am still receiving bills threatening legal action for a gas supply that they are no longer providing and haven't been for a year now.
The level of customer service they provide is more or less no existent I appreciate I have left the company but all this situation does is reaffirm that leaving SSE was a good decision and I will not be returning at any point in the future.
This is now escalated to the Ombudsman as it has taken well over the 3 months that it should take for them to effectively handled what should be a very simple task of closing an account.