only 3oom from exchange max speed up to 8mb

I have Eircom BBand for a good few years now, recently E-fibre has become available in the town, but I am direct connected to the exchange. There are plans to put in a solution for direct connected lines but it will take months if not a year or more. I am only 250 metres or so from the Exchange but am only getting up to 8MB, in reality 6.6 mb. I looked for an upgrade in speed only to be told the test was reporting max 8mb.

I know some of the local engineers, I asked one to check the line for me. He told me there was a line imbalance of 20% showing cause by bad cabling in the exchange, which indicated that my line was more than 5 km from the exchange. He fixed this and told me I should get a much improved speed. I asked for a retest and it came back the same, max 8 mb. I challenged this with faults, explaining about the improvement in the line balance etc. They agreed to have another look and he said it was something to do with the port I was connected to in the exchange, the Tec already mention Dslam and Isam but I got lost.

They sent me out an updated router Huaweii F2000 which made no difference. What I am asking is that the difference in the fault from 20% imbalance registering at over 5km distance back to almost 0% less than 1km is too big a difference not to show an improvement in my max speed or am I completely wrong.

Any advice would be most welcome please...