From hard-won (and very, very expensive) experience with Peugeot:-
1. Insist on a copy of the job card after the work is done. This is a
record for you of them having looked at it. By default most Peugeot
dealers will try to avoid giving you this - one even tried to claim to
me that I had no right to have it as the work was being paid for under
warranty!
2. If they say there is no fault, then insist on trying an equivalent
model for them to demonstrate that this is normal for that model (it is
always possible that they have a feel that you can't get on with, in
which case the only solution is to buy another car with properly
designed steering).
3. If they say there is no fault and the steering is working perfectly,
insist that they put that in writing, and ask them to have the car
examined by Peugeot as you consider it unsafe to drive.
4. You may have to get a report from an independent motor vehicle
engineer stating that it is unsafe - that will cost you money but will
be invaluable when (if) it comes to taking action against Peugeot.

At all points, make sure you have written records, because from my
experience (and that of many others), Peugeot will _not_ act honourably
and you may well need those records if it comes to court action.

Matt