iPhone Charger not working, help?

I had the iPhone 4 before and ever since I got the iPhone 5C the chargers I have gotten have been messing up. Every charger I have, works for awhile but then it stops working. I orginally thought it was because they're just the chargers that come along with the pack but then I tried using a more exspenive charger and the same thing happened and it says "this accesspry may not be supported". This did not happen when I had the iPhone 4, I could role it up and put it in my bag and or I could use it whenever I wanted and there was no problem. This has been botering me because I dont have the money to always buy a new charger, can anyone help? and I was also wondering if it's actually the charger? or if it's my phone?