You can fix it yourself. You need two regular "F" connectors and a female to female joint. Fit an F connector to the ends of the cut cables and then connect the two ends using the joint. Tape over the whole thing using self-amalgamating tape. Geyt all this from a good DIY store.
Beware do this with the Sky box unplugged from the mains and the signal cable disconnected and don't short any of the wires when you are fitting the F connectors. This is because the cable carries a small voltage. Get it wrong and your Sky box is toast.
Terry
October 2006