Sprint customer service/ retention paid etf then they said i owe $290.00, Internet

       I inquired about an upgrade phone due to mine being discontinued after being promised that after 1 year i would be eligible for upgrade to evo 4G xxx, As i was about to pay my bill the csr informed me that it would cost $300.00 ???? whoa then explained to me that these phones cost $600 to $700.00. so i asked why was i not informed about having a 4 g pkg and a phone they pushed on me with cutting edge technology of 4 yrs ago and me paying extra for the data pkg? reply ant smartphone requires this and a few more services wow i paid a whopping $142.00 per month for a phone not capable of doing the 4 G JIG! and after asking for a price reduction i was told flat out no with emphasis  and i paid the 110 etf and the csr notified me that i owe $293.00 when i went to the sprint buyback the same phone worth $293.00 was worth a mere $11.00 !  laughing trumpet wah-waaah! goodbye sprint hello prepaid