iPhone 5 Lightning Port Problems

Hi, I have been having problems with my iPhone 5 charging recently where I have to keep holding the lead to the left in order for it to charge. Once I hold the lead to the left it charges again bit then it will stop after a few minutes and I have to plug it in and hold it to the left again for it to charge. I've read about it online and it seems to be a common problem for iPhone 5's. I know it's not the charging lead because it works fine with my iPad Air and I have also tried it with different leads and it seems to still have the same problem. There is no physical damage to the phone and I have never dropped it. I still have my Apple one year warranty as I only bought it last September. What should I do? Any help would be grateful.