balljoints and steering column?

Seller replaced an upper balljoint on the w211 (2007) when I bought it a few wks ago - now it's started squeaking again from the front when warm (as far as I can tell anyhow doesn't seem to do it all the time). Plus, serious cranking noise and not smooth steering when steering at almost dead pace e.g. driving out of driveway or reversing in.

Any thoughts ? I've read all the ball joint issues and this sounds like it but what about the juddering steering at such low speeds - is that consistent?

many thanks !!!
John.