I work in a very small team. There are only 3 of us and I am the second most senior and I have been there a number of years. I have a fairly new colleague who I think isn't paid very much. I sit next to her so I can see her computer screen. I've noticed that she doesn't do anywhere as much work as me and my manager (we have a system where it's obvious what work has been done) and I realise that is because she is on messenger a lot of the day or looking at her phone. She has just been given a pay rise. I haven't. I have had a problem with childcare so have had to do shorter weeks and so have not been in the office as much but I am still doing 3 days a week as opposed to my normal 4 and getting all my work done. Now I have an appraisal next week and I am incensed that someone who does so little work has got a pay rise but I am wondering if I should mention it in my appraisal. I am quite friendly with her and so feel it would be very two faced of me but I feel that this is an injustice. What shall I do?