Thanks for the replies. I've been reading a number of the previous threads and there's some great info.
I knew at the time I bought my apt that no dishes were allowed and I was ok with that. Didn't bother me either way. However, I was forced to sign up for Chorus or have no TV. The apt was piped for Chorus and I was told NTL or any other service was not available in the development. I reluctantly signed for Chorus but after months of frustrating service, poor reception, no additional channels etc etc etc, I decided to go for Sky. I looked around the estate and saw numerous dishes erected and as the estate was a few years old I thought it would not be an issue. I do realise just because everybody is doing it doesn't make it right, but I went for it anyway.
Now I receive this heavy-handed letter telling me to remove it within 7 days or else. Considering that every time I try to contact the management company about something I'm ignored or told 'Sorry there's nothing we can do...' I find this quite insulting to be honest.
I do realise they are within their rights, so I suppose the only thing I can do is ask them nicely to allow me to see out my contract with Sky... another 7 months.