Hi,
What do you mean by wrong increment letter? Increment letter with wrong numbers / increment pertains to some one else wrongly given to other person. Whether the increment letter was emailed or hard copy issued?
If you sent the same by official outlook email id. if so use recall option and get back it. (The original message must still be unread in order for Recall to work. If the message has been “read”, then the recipient will still receive a request that you want to Recall the message). If hard copy issued call the employee and get it back.