It sounds to me as though you need to do a manual scan. The following instructions are courtesy of Big-les over on Digital Spy:
The reason for doing a
Manual Search is to target the six (five after DSO) multiplexes coming only from your preferred transmitter. The UHF channel numbers for your six/five multiplexes (digital channels) from your preferred transmitter can be obtained from the
digitaluk web-site, enter your post code and also tick the "I am in the aerial installation trade" box. Your UHF channel numbers are in the grey columns in the
Coverage prediction section. The compass bearing for the available transmitters at your address are also shown on the page so you can check to see which transmitter your aerial is actually pointing at. You should only use the transmitter that your aerial is pointing at.
First you need to delete all existing channels.
Menu > Edit Channels > Edit Channel Lists > Password (0000) and delete all channels, note there is a
Select All button. If you were on a TV channel before going into the menu then TV channels will be listed first, delete them all. Go to
Group, select
Radio and delete all the radio channels. Press
Exit on the remote control and when invited save all the changes.
You will now get a message saying
No channels are available……, press
OK. You should now be taken to the
Installation menu, choose
Manual Search. Select the first UHF channel number obtained from the digitaluk web-site for
Channel (actually the order doesn’t matter) and press
Search. When the search completes,
Save. Select the next UHF channel number for
Channel and press
Search.....
Save. Repeat this for all six/five UHF channel numbers and to finish press the
Exit button. You will now find all your Freeview channels on their correct channel numbers, good luck.