Rude supervisor at returns/exchange desk

<p>I bought a cordless house phone earlier this year in march, it wasn't working so I returned it, the exchange only contacted me last week to tell me I must come for my money. My mother took the exchange slip that I signed on to the store with the reference for my exchange to get the money back. When she got there she was asked for the receipt, which the lady at the store took in March and told me I won't need again, so my mother told her that and she said that "your son in lying" and walked off mumbling in her language, after intentionally taking a long time she came back to give my mother the money. This rude behavior is not what I expect from a store and especially towards my mother. She is a supervisor and treats people so badly, she deserves to be fired.</p>