Compaq preserio 610
Hardware problem

I have purchased a laptop model preserio 610. After sometime its adapter has some problem. When i went to the service center they asked me that the adapter serial no. does not match with the serial no. of laptop so they can't replace it. The sales man from where i have purchased it said that it is possible that the charger may have interchanged with any other latop's adapter, But in that case what can i do? He said that there is no solution to this problem. Now what should i do please suggest me