Firstly, find out if your company has a guideline on such matters pertaining code of conduct of salesperson. This would give your case a stronger boost when you speak to your manager.

Calmly explain the situation to your manager and. However, you will first need to get concrete proof that your colleague did steal your clients – speak to your customers to ask if your colleague did indeed approach them with the intention to poach them away.

Lastly, be careful around the office. Try not to share too much information about what you’re doing and always keep your computer password protected whenever you are away from your desk. You can never be too alert in a dog-eat-dog world.