Speed Drop after Openreach engineer working on neighbours line

[#1]

Yesterday and Openreach engineer was working on the line (supplies 9 houses only in a cul de sac). Immediately after I could tell that the line speed was suffering. overnight the sync speed which  has been constant for a couple of weeks dropped from 52.2 to just over 50. data trasfer speeds down accordingly. what might he have done which woujld alter my line speeds. upload is particularly affected and is very up and down during test. download is just down a couple of mb. can this be rectified?

[#2]

What speed does the BT checker show as the likely range for your line? What upload speed are you getting?
The slight speed decrease could be down to crosstalk caused by a neighbour having FTTC installed rather than it being a fault.  "The line" that you have isn't shared by anyone else and it doesn't serve 9 houses.  Your line will be sharing a multicore cable along with lines from neighbouring properties however.

[#3]

Poor use of language on my part - thanks for the reply. I understand that the properties are served by multi core cable and that I am on one twisted pair. the issue was the drop of sync speed and what might have caused that. perhaps one of the plusnet staff can pick this up and test the line. it was repaired a few weeks ago and the speed picked up. at that time a battery fault (two lines shorting out effectively) was the cause