I am going through a complaint with them at the present time. I was an SSE customer, for many years, who was migrated over to Ovo energy. I never had a problem with SSE billing and always paid anything owed to them, correcting any estimated billing if it wasnt near the actual usage, then a correct bill was sent out from SSE. I can honestly say that I've never experienced a billing system like the one I'm receiving from Ovo energy. They seem to be moving their estimates around from month to month. Ive never had DD with my energy company and I pay what I owe to the energy company when I get my bill, and I would advise anyone who can to do the same. Bills from Ovo are messy, inaccurate and really difficult to understand. They are monthly instead of quarterly for me me now. I implore anyone who is having any difficulty understand these messy, incomprehensible bills to complain until the complaint reaches the energy ombudsman. Ovo has already been fined 8.9 million in 2020 for inaccurate, complicated billing. They need to change their billing system ASAP so it is more transparent and accurate.