Sagem dv3 digibox - max no of channels?

I've got 2 of them. Over the last few weeks they both claim they've found new channels whenever I turn them on. I do a scan and save but a few mins later it says it's found new channels again. I already have 90 channels on each - is there an upper limit on how many they can have? Can't think it's a h/w fault as both boxes started doing the same at the same time.
The only way I've found to stop them keep asking me is to break-in and exit during scan, wait for the "network name" message to say ?, press back, let it restart rescan then break in and exit. A single break in and exit doesn't work - the new channels message just comes back again after a short time.