Cant remember if I have flown a 180C without looking in the logbook but the PA28's that I have slipped come down quite nicely when applying a slip.
You dont mention your experience and from what I read between the lines (correct me if I am wrong) you may well not have a lot of experience and that may be the issue.
As others have stated some machines are not allowed to slip and this should be explicitly be mentioned in the POH.
If it is an experience issue you would best find an instructor that can show you how to properly slip an aeroplane. To be honest I think that need not necessisarily be in a PA28 (although it would not hurt) Slipping is a bit like riding a bike or driving a car. Once mastered the skill is readily transferable between mounts.
Most difficult bit of the training is probably going to be finding an instructor that can teach you this properly.
Have fun.
FD