Can a 4 year old Skybox got on one payment,have lost receipt,can be fixed?

I obtained a Sky box for a friend 4 years ago,It was bought on a once only payment she did not want pay channels.She had it because one of her free channels was EWTN Catholic channel.Her aeriel is communal,in her flats. She has been told her box might be faulty.As I have lost the receipt.,and Sky states they have no record.Can you tell me if anyone can fix older boxes