I’m so confused with what T-Mobile is offering me with a line upgrade for 18 pro max, help!

They quoted me $1025 off for the $1300 iPhone 18 pro max plus $175 if I trade in my iPhone 13 Pro Max. That would be 1200 off the iPhone, yet they’re quoting me $11.45 a month fee for 24 months (which would be 275 dollars). Shouldn‘t the total cost of the phone be 100 dollars or 4.16 a month for 24 months? I’m so annoyed at the lack of an explanation from customer service that makes any fucking sense. Please help!