The regulator said "misleading and unsubstantiated statements" were made to potential customers about prices and savings that could be made by switching to the energy provider.
SSE has a £5 million mis-selling fund in place, from which customers can receive compensation if they have been mis-sold products.
Ofgem is encouraging anyone who believes they have been a victim of mis-selling to by SSE to call the fund’s dedicated line on 0845 0707 388.
In a statement on its website, SSE said it believed:
All customers who may have been financially disadvantaged as a result of the breaches should have received a letter alerting them to the Sales Guarantee nevertheless, our dedicated team can be contacted on 0800 975 3341.
In April 2012, EDF Energy agreed to pay a £4.5m fine to help vulnerable customers for breaching marketing licence conditions.
Ofgem is also conducting mis-selling investigations into Scottish Power, Npower and E.ON.
The Citizens Advice Bureau offers the following advice to consumers that have a complaint against an energy company.
- Make your complaint by letter, telephone, online or by email.
- Make sure you keep a copy of anything you send, including energy bills and note when they were sent.
- Energy suppliers have a set time limit in which to resolve most complaints. The time limit is eight weeks for the big six energy suppliers or 12 weeks for smaller suppliers.
- If you are happy with the way your supplier is handling your complaint, you can ask for an internal review.
- If you want to take the complaint further, you can contact the Ombudsman Services: Energy. In NI, you can contact the Consumer Council for Northern Ireland.
Other organisations that can provide assistance and advice to consumers on resolving complaints with an energy supplier include: