Help revert changeset

A new user appears to have made their first two edits (changesets 12553650 and 12553082) in error.
They have created a long untagged way, and in doing so, have moved some other points on the map (Eg Bow flyover [node 1844462094] in London UK).
I emailed them twice (3/8/12 and 15/8/12) but no reply.
I am not confident to revert someone else’s edits.
Please help revert these two changesets before it gets any more complicated.

There is already much time passed by since the faulty changesets.

So maybe it is not so easy to revert the changes.

Hints can be found at

You should contact any experienced OSM wizzard on the main OSM IRC channel to go on.

I had to learn how to use IRC, but most of the problem has now been fixed by the OSM wizards, the rest I am doing manually.