I AM NOT ABLE TO UPGRADE MY CONTRACT DISADVANTAGED

I signed a contract on the 15 May 15 a Iphone 4s, which took so long to charge in store. it was 18.39 that i received the phone as per a receipt that i received. NO COPY OF CONTRACT. i thought the guy helping me would have put it in the packet with the phone, it took another guy about +-45 min to wait to sort setting on the phone. so when i got home i was not happy with battery life as i was not using the new phone as my current phone contract only expired on the 29/05/15. i felt that no apps loaded and batteyr life not that good so i went to the store the foll friday 22/05/15 to ask if i can upgrade to the Samsung galaxy A3 as i am not happy with the battery life and as per the consumer protection act i returned the phone on the 7th day in the same condition as i received it. i even mentioned that i did not receive a contract where i could read the terms and conditions . i did sign where the person helping me said its for confirming my banking details and receiving the phone. AM REALLY UNHAPPY as i feel the person helping me should have shedded some light on the phone as it is my first time with an Iphone. there was no sample phone in store. he did not offer me choices etc