Changing Pairs

I am dealing with a mate of mines internet. He lives close to the
exchange and people on the same pole as his get some good speeds but
he gets so much lower. I understand that the route that his line takes
could be so much different. But I was thinking of asking his ISP to
change the pairs, but was wondering what they would actually do. Would
they change the pairs at the pole and the exchange so t hat he was was
running on a new pair from his house to the exchange or would they
change something else. The first one would make sense as I believe
that the pairs are matched to phone numbers at the exchange. Thanks
for you help.