After 3 months of declining speeds(20-70kbps), a number of emails which never got an answer and 7 phone calls (average holding time 40 minutes) I got a visit from a very helpful team. In ten minutes they identified that the sector I was allocated was saturated and changed me to another. That consisted of changing one digit in a setting!

Immediately 1.92MB down and 5MB up, rock solid!

All I can say is that the system can handle what is promised when adjusted properly on most transmitters. Some are absolutely saturated in every sector such as the Guinness site. IBB are simply doing the equivalent of overbooking in airline terms - selling capacity that they have not got. In my experience, people who get broadband use it so banking on the fact that they may not is not a proper business model.

Advice on making contact to improve your circumstances - ring Accounts as for setting up as a new customer. Make them aware that they have to look after the existing ones before selling more and diluting the resources