DISEqC switching decocder?

Hi All

Some help with this would be really appreciated, I am not a satellite genius like you lot!

I have a dish setup in a French property, appears to be unicable to a wall socket. There are 3 dishes input to the system, set up by the local installer.

He has set up:

- DISEqC A pour AtlanticBird
- DISEqC B pour Astra 19.2
- DISEqC C pour Astra 28

He says I need a decoder with an internal DISEqC switch, does this sound right?

Can anyone recommend a good decoder or setup? Thanks!