Damaged shoe

I bought a shoe for my son he only wore that s**** for 15 days and the heel was damaged and the glue also comes out; I sent it back to waterfront store they told me they gonna send it to manufacture and it’s not factory fault it’s the way my son walk of which it’s not true he can’t wore a shoe less than a month and then it’s damaged . They called me yesterday 01/02 to tell me I need to pay R155 for them to fix the shoe. Imagine that shoe it’s not even a month his wearing it. I am so disappointed