Sorry to hear that, it's horribly frustrating! I know it can happen, I had the same experience with my first pen. It did improve after I re-bent the two halves of the nib and used the bottom of a ceramic mug to smooth the tip of the nib. But getting a new pen was the only solution that really worked.

If you're sure you're holding them correctly, so the problem is not the posture, try to buy either pens with a guarantee from the manufacturer (so you can get it fixed), or a pen in a shop that will let you try it first. Not all nibs are manufactured equal...

A good pen should glide much better than a gel ballpoint.