to be honest i'd recommend calling the phone number i gave in a prevous post.
My issue was resolved by going to
http://192.168.100.0/gscan.htm
and then checking the start frequency
the correct frequency for me is 331000000 and then click the link to reset the modem - you may have to do this a couple of times for it to stick
I am now monitoring the situation, i haven't been disconnected once since i did this - however if it continues i have to call back and the next step would be a replacement modem.
Take your pc/laptop and connect direct to the modem (bypass wireless router etc) before doing any of this