Problem with my iphone 4

Please am using one iphone 4 and since yestaday when i am charging it then it goes off and turns on again several times.
When i tk off the charger too sometimes the phone goess off.
When i on it too sometimes the reception doesnt come it says searching...but the 3G shows....when the reception comes too and i try to make a call it doesnt go when i try callin de iphone too ut doesnt show but is going through too..when i send a message that one it comes...i dont know what to do..i want to know wether it can b fixed or i have throw it away