iphone warranty
Hello, my father bought an iPhone 5 in december 2012 and when i took it at the beginning of this year i found many problems like bad coverage using many operators and my wifi signal compared to my friend's iPhone 5 standing from the same place is weaker than his plus i had a battery issue and i replaced it in a reparation store not authorised by apple and now the battery problem is back. Can i contact apple? will they find out that i changed the battery? I read on apple consumer laws -Europe,France- after the warranty expiration can change or fix the device if proven defected. What can i do?
Thanks in advance
iPhone 5, iOS 8.4