Tomorrow I am meeting with someone I have line managed for a few months to discuss their performance. They are overall good at the job, however I have concerns about their attitude and manner in the customer facing part of the role. Other members of the team have reported to me that they can be quite rude and I have witnessed some borderline unpleasant exchanges had. I've intervened but perhaps not firmly enough.
In the past, I've managed to talk through areas my reports have struggled with through identifying support such as extra training, buddying etc. I think a big part of this however is who they are as a person. They are very strong willed and don't really care what others think. Any ideas on how to approach?