I was with Lumo for 18 months. While the experience during that time was acceptable, when it came time to move things got messier.
I called and notified them that I wanted a final read and disconnection.
They issued me what I (incorrectly) believed were final bills.
6 weeks later I get an e-mail from them with a bill, which comes as a surprise. They have charged me $31 for supply of electricity but unsurprisingly $0 for usage because the property is vacant.
I gave them a call and spoke to Rani who was helpful but said there was no record of me calling to arrange disconnection and that it is impossible that I called because they have no notes on it.
If there's one thing I can suggest taking from my experience with them is keep a spreadsheet detailing names, times and purposes of every call you make to them.