Name changed as this may be outing
More of a WWYD I suppose but I'd really appreciate help/advice
I've been with my company (admin work) for a long time now, always get good appraisals, the go to person for most questions etc. I have been working towards a promotion fir several years now and my manager was supportive of this but the position itself was not in the budget yet (other similar teams had this role but ours didn't). I've always been a very hard worker but at the start of the year, I became mentally very unwell and had to take some time off. I'm getting help for this and believe it is due to a medical condition which I should be getting sorted soon.
Anyway, whilst off sick, the position was made available and was posted internally. The deadline for applying was whilst I was away and no one informed me of this. I have come back to another, not so senior colleague, having been given the role. Im really upset. Just spoke to ACAS who advised me to raise a formal grievance but I am not sure what the point would be as the role had been given to someone else now. I assume I would have to give a preferred outcome but what would I say, there cannot be 2 people in this role and they wont compensate me financially if I am not doing the extra work? But at the same time, I don't think they should be able yo get away with it. What would you do please?