Hewlett Packard - Manufacturing Fault from the Date of Purchase

we had purchased one laptop for one of our senior team member from HP, however from the date of purchase we had lodged * times complaint but its still not running successfully. based on the discussion with one of engineer who were aligned for this complaint he is not qualify enough to diagnosis the issue from very first day. now hp doesn't want to take the responsibility to replace this due to doa ** days clause for replacement. again they are saying we can attend the complaint one more time as they did * times earlier.