Cruise Control doesn't always work

[CplSmudge]

I recently lost the offside indicator glass on the mirror, took about 10 days to get a new one and fit it but since then the cruise control seems to decide not to work now and then.
I did wonder if rain getting in somewhere might be the cause but the glass / plastic has been replaced for over a week now and it is still happening.

Any one got any ideas?

[loot]

Get fault codes read on ids it could be a few things including faulty buttons