WARRANTY WAS OUT BEFORE DUE DATE!!!

I bought a contract LG G4 phone with MTN then it couldn't charge anymore and took it to the store with everything of it, they said they will send it for warranty assessment, I was left with 2 days in my warranty and they said the warranty is over, 2 days is nothing but they will submit it, I was shocked that how can you say it's over when i still have 2 days of warranty, when i called them after 7 days they said my phone is rejected and there is someone who worked on it already. to my surprise that i never had anyone working on my phone, it just couldn't charge no more then i sent it back to them. they said I should book it for normal repairs and it will incur charges. I'm very disappointed with this! MTN is ripping people off, the sad part is that I'm stuck with this problem which it's not my fault, they sold me a bad phone !!!!