Do you have any proof? No offense to you, but this sounds like a ghost story to tell in party chat around a campfire of some sort.

Look, I get that it's frustrating, but to be honest, the skill tier system will, without a doubt, move you up if you deserve to be moved up. Perhaps you just aren't improving? I find it exceptionally easy to progress through lower tiers when I sink from losing streaks, but always find myself staying in the same tier range for long periods of time. It's because I belong at that particular tier at my level of skill. Just keep working at it, and play in parties of people you trust often.