I have always thought that Cable Modem support phone calls should be free, (if its a general NTL network fault you should be credited, especially if you have to wait over 45 mins listening to an automated voice apologising & telling you that NTL loves you)
Back on topic
If your only getting 60-80kb/s on NTL's Gold service then there is a problem somewhere. (If you change isp's and you get the same speeds for a 1meg service then you will know where to look).
In some areas changing isp's because they are cheaper than NTL it doesnt mean you will get faster speeds etc. The internet
does slow down from time to time & other isp's do have problems with their services.