I've been working in a Customer Care Role (Remote) for about two years and within that time, I have been seconded twice to a Senior role and would say that I am pretty good at my role which is backed up with my weekly meetings with my line manager - who always tells me that my KPI's are amazing and usually I am in the lead within the entire Customer Care team numbers.
We also do admin work in CC and I have trained up others in this specific thing called 'return escalations' and have also created a training spreadsheet on it for new starters to go through on their induction day which shows me that I'm in a trusted position to do this.
In the past couple of months, I've noticed that a colleague who I trained up is always being put forward to do other things within CC, meaning she is increasing her skill base whilst I am not learning anything new.
Recently she applied for a new role but was unsuccessful and was told that she can get trained up if she wanted to learn more about it, however this is something I would have liked to do too but I never applied because I had none of the required skills, neither did she. I have voiced my interest about this area numerous times to the person who is actually in the role and told my line manager I'd like to learn more about other areas in CC. Nothing happens for me yet the colleague is on training all the time to step into specialist roles to cover their annual leaves yet I'm just doing basic customer care - especially now I've trained up others, I barely do anything else now because they're all doing the return escalations now.
There is another colleague on annual leave, she did a huge handover to cover our her roles which is a really interesting area within the business, my line manager was CC'd into the handover so knew about this but the whole workload was handed over to another colleague to do whilst I covered the work for a colleague who was off sick, I learned nothing new and anyone in CC could have done it, we all are trained to.
How do I address this with my manager?
Would I do this during a weekly meeting or shall I put this in the form of an email?