Unwanted Touching

My manager keeps touching me on my shoulder whenever he walks past. It makes me feel really uncomfortable because I don't like being touched or having my personal space invaded. I want to ask him to stop but don't know how to approach him, especially because he is my manager.

Constant Shouting

My colleague who I work with regularly shouts at me and it is really upsetting. There is no reason why she keeps shouting and I don't know how to ask her to stop. I don't feel able to go to my manager to complain because I don't want to be seen as a snitch.