Incorrect dispensing of medication

I have been collecting my medications for years from, checkers Raslouw. And i went to collect medications for my son the one day with a terrible migraine. I just signed the form.for.the medications dispensed. When I went to collect my sons other medications on script I was told that I took it twice in one month very arrogantly. And I said I did not . They insisted their stock balances. Like I was lying. I did not take two boxes. Why would I take.two.boxes in one month. I laid a complaint. I get a call that they will do me a favor to.give me another box. I don't need the favor my Doc gave me a new script. I want to know why there is two boxes issued on my son name. When I only got one.. I still don't have an answer. How far must I go to find out what happened. I don't.like being.made to feel like I am.lying for something i did not.do.