The scale plan tier threshold is too high . I wanted to fix it at tier 3. This goes beyond my budgeted amount

The scale plan tier threshold is too high set at 8. I wanted to fix it at tier 3. This goes beyond my budgeted amount. I am not able to change it manually. Also wanted to change the tier to Tier 2. I tried once mid of the month, I was charged but nothing changed from tier 1.

Please help change and adjust the plan.