Partiality in ratings

So I have been getting average ratings but good feedback from my manager. When I directly confronted them regarding this, they said that average rating was impossible as they have been giving me good ratings all through the year. When I showed them the proof, they said it’s a technical issue and they will do something about it.

Even after reminding them twice, all I am getting is fake promises. Now I am scared and demotivated to remind them again as I feel they may dip my ratings even lower by getting irritated. I don’t feel like working these days because of this. What should I do on this case?