The engineer came today, I asked him if he knew the situation and he hadn't been told anything by the phone workers...and as soon as he walked in he said "Ah you need a new modem" I was like
yay someone actually knows their stuff. he said he's had to replace a lot of the terayons on the 4MB and 10MB service mainly, and he kept saying how the message should get across to the phone workers that these things needs replacing, which is exactly what I was thinking.
He was done within 15 mins giving me a new 250 modem and everything works fine. Great work.