Initially, if you experience a problem, you should contact your service provider's customer services department or account relationship manager (if your business has one) and explain your problem.
If that doesn't resolve the issue, you can make a formal complaint to the company. Complaints will normally be escalated through the standard procedures set up by the company.
All communications providers are required to have a Code of Practice outlining how they will deal with customer complaints made by residential and small business customers.
You should find details of how to make a complaint on the back of your bill and on your provider's website.
If you can't find these details, the company's customer service staff should tell you how to make a formal complaint.
Remember to always ask for a reference number when making a complaint.
You can also complain to Ofcom by clicking this link. Please note that Ofcom cannot process or take action over individual complaints. However, we use complaints data to help us identify cases where enforcement action may be required and also to highlight problem areas where other regulatory action may be appropriate, such as the introduction of new rules to protect consumers and/or businesses.