I am extremely sorry to hear the same problem has occured again.
As per our meeting about this problem on May 14, 2015. We have already done as your requirement such as recheck and marking circle after part's name on products.
For the documents which our staff sent to you on May 15, 2015, this is part of document of our process.
However we are always trying to improve our process to prevent this problem.
Sorry again for late reply and our mistake which make your inconvenience.