The Punto is a heavy car, it has good road manners and has a stable ride quality. The comfort level is good on the Punto but better on the VW Polo. The other point that the Punto scores over the Polo is that of a 4 cylinder engine while the Polo has a 3 cylinder engine in both Petrol and Diesel variants.
Sir, if all the engineers are saying that there is a problem in Punto than they might be right, then you should test another Punto in same variant for that problem. If you feel the same problem in the other car also than the engineers are right. But if you won't found the sane in test vehicle, then there Might be a problem with your tyre or wheel or it might be a problem in suspension system. If the problem is with tyre, then it is a regular problem. But you are saying that the problem appears when it just jumps over a bump. By this, it is sounding as a problem with suspension system.