Faulty phones

I had an iPhone 5 for 2 years and the front camera stopped working - so I paided £25 excess for a new phone. My phone didn't come for weeks and when i rung to ask why someone told me that the iPhone's were faulty so they couldn't send me one till they fixed it. So I returned to uni without a phone. Weeks later I came back to my new phone, but it wasn't long before the phone stopped working and stopped charging and stopped turning on. I can hear the battery moving around inside the phone. I turned the phone over onto a table and was shocked to see a crack on the screen. Considering I had a screen protector, this was a bit weird. I know phones don't break this easily as my old phone was in perfect condition. Now fonesafe are asking me for £75 for a new phone due to the crack when the phone is definitely faulty. I am left phone less currently as I refuse to pay for this as its £100 all together and I'm expecting another faulty product.