I've been told differently about upgrading my phones by different Agents. With the Samsung S23 Ultra , trade in 2 S21+ I get $800 per phone. I'm told by different I can upgrade in 24 months. Other Agents say no 36 months. The ones saying 24 months say as long as at 50% paid I can upgrade. Nothing was said about I'd lose my credits. The 36 months Agents say I'd lose my credits. Who can I contact for clarification?