Openserve still cannot solve my ADSL speed issue.

I have had a 4meg ADSL line for the past three years without a major issue. In June 2018 the line speed went down to 2meg. I have had Openserve guys here a number of times and they can't seem to fix it. On Thursday the 24th August one of their "specialists" phoned me and tried to tell me that it is because of the distance from the exchange that my line speed dropped and when I told him that it has been working for the past few years and 4meg, he tried to b****t me with another sob story. One of the other Openserve teams proved that there was a problem on the v-side to the dp, but this "specialist" would not believe them. I think they are called "specialists" because apparently they work with laptops. Can somebody from Openserve with some savvy please sort this out for me???