The Grande Punto is a good large hatch, fit and finish is of good level and after sales is managed by Tatar Motors so that also helps, expect 12-13kmpl on the Petrol Punto. The Fiat Punto is good enough for a family of 5. Also check out the Hyundai i20 which falls in the same segment.
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.