Is it possible to block a number on a sky landline?

What is the best customer services number to use?

thanks in anticipation

Outgoing block?
Or a block on someone calling you?

A block on someone calling me

A bit expensive but you can get a device called trucall, that connects to any landline phone that you can select what numbers you want to block.

http://www.truecall.co.uk/

Sky have got a barring system to stop selective calls
http://www.sky.com/helpcentre/talk/s...aller-barring/