We have Canal + and have also had this problem once or twice.
We treated it like any other electronic device and switched it off completely at the box
(using the switch not the remote) and then after a minute or two switched it on again.
It was all back to normal.
If that doesn't work you will need to contact them, but it is now owned by Movistar.
You can request that they phone you or use their online chat service: