Three weeks since my issues were finally resolved and I'm pleased to say that I've not had a single issue since
I've noticed that upload is no longer maxing out at 750Kbps but is consistently around the 600Kbps, zero packet loss and download continually maxing out. This was the service I used to receive, this is the service I'm now receiving again, this is what I'm paying for!
Still not managed to get on XBox Live as a few days after the fix my router started randomly disconnecting, switched routers and all is fine. Just hope it lasts, couldn't go through another seven months of the problems we had.