It’s imposible, the updates are coming to everybody, each Tuesdays and Thurdays without any trouble. Could you ping the avast! servers?
http://www.asw.cz/iavs4pro (IP: 195.70.130.34)
http://www.avast.com/iavs4pro (IP: 64.246.6.135)
http://www.iavs.net/iavs4pro (IP: 207.44.156.15)
http://www.iavs.cz/iavs4pro (IP: 62.168.45.69)