It is important that you contact your energy company first to let it know what's happened.  A good place to start is the general enquiries number that should be on your bill.  Hopefully the company will be able to sort out the problem at this time, but if not you should try to escalate the complaint within the company.  To help you with this, your energy company will have a complaints handling code of practice which explains how the company handles complaints about its service.  This should be available on their website or as a leaflet which you can ask for.  You should make every effort to follow this process.

Remember!

• Before you complain, make sure that you know what you are unhappy about.  Is it that your bill is wrong?  Is it that someone has been rude or unhelpful to you? 
• Stay Calm!  You are more likely to get a good result if you don't let your emotions get to you.
• Be clear and concise.  If you are ringing about your complaint, make a note about what you want to talk about before you make the call, so you don't forget something.  Also, have an idea of what the company could do to make things right for you.  If you don't feel confident enough to speak to someone, try writing a letter or an email.
• Keep a record of what happens.  Keep notes of any calls you make or any emails or letters you send.  Also keep any correspondence you get back from your service provider.  An example of how to do this can be viewed here
•  Don't give up!  There are other organisations that might be able to help.

You might get a letter from the company which says that it will no longer be handling your complaint and this is its final position.  We call this a 'deadlock letter' and you should let us know about it.