they overcharged me and dont want to pay back

They overcharged me on the 9th of september and i went back to report they told me they wil fix it and get back to me but they failed, wen i went back yesterday they told me they wil cal me today but failed, wen i went back today the manager told me that was not a ****a shop,i dont know if he is desrespecting me coz i work at retail or coz im black, ive got bank statment to prove that they took my money,