By Torin Douglas
Media correspondent, BBC News
Freeview's website has been providing details of the changes
On 30 September, Freeview is making a number of changes which means users of the service will have to retune their set-top boxes.
We look at what is going to happen and which services are going to be affected by the update.
What's happening and when?
On Wednesday morning, 30 September, the Freeview service is being updated. Some TV and radio channels will move position. If people don't retune their equipment they will no longer receive them. The move involves around 25 million Freeview TV sets, set-top boxes and digital recorders, including TopUp TV and BT Vision boxes. It doesn't affect satellite or cable systems such as Sky or Freesat or cable.
Why is the change needed?
To make channel Five available in half a million more homes and to prepare for high-definition broadcasts.
How do I retune my set-top box or TV?
ROUGH GUIDE TO RE-TUNING
Switch on your Freeview boxPress the menu button Select "set up" or "installation"You may be asked if you want to delete all your channels. Select "yes". They will be restored later. Some boxes may ask for a security code. If you do not know yours, the factory setting is often 0000 or 1234.The update should proceed automaticallyWhen complete, your box will shut down and restartAfter re-tuning, you may need to reprogramme your favourites listOwners of a Freeview recorder should re-set future recordings
These instructions may not work on all equipment. For complete instructions, refer to the manufacturers' manual.
The exact method of retuning will differ depending on your make and model of Freeview TV set, set-top box, digital recorder or PC viewing card.
However, in most cases, you should find the option to retune after pressing the Menu button and following the on-screen display. It is important to perform a full update - which deletes the existing channel line up and starts from scratch - rather than an automatic scan, which simply looks for new channels.
Your instruction manual should provide more information. If you have misplaced it, check for instructions on
(NB the site is currently experiencing difficulties due to a high volume of traffic). You could also contact the manufacturer or your local electrical retailer for help.
What happens if I don't retune?
On the affected channels, you'll see a message telling you the channel has moved and asking you to retune. Anyone who needs help can find it at www.tvretune.co.uk or via a telephone helpline - 08456 05 11 22.
Which channels are mainly affected?
Five will stay on the same channel but will become available to more viewers. Some households - about 3% of Freeview users - will lose access to ITV3 and ITV4. There will also be a new TV channel called Quest.
Some BBC radio stations will be affected in areas that have already gone through digital switchover. Listeners in the Border TV region, the West country and some parts of Wales will lose these stations unless they retune.
Will some channels disappear altogether?
Around 460,000 homes - which get their TV signals through relay transmitters - will no longer receive ITV3 or ITV4. That means they will lose some European football matches and classic TV dramas such as Cracker and Poirot.
The Community Channel will no longer be available on Freeview in areas that have gone through switchover.
Can all Freeview equipment be retuned?
Around 22,000 older set-top boxes may no longer work.