Billed on iten I didn't get or purchased

On the 17th of December 2021 did shopping at this specific store. When I got home to fit the kids the clothing I noticed on till slip I was billed on iten that I didn't purchase. I then called the store and since then I have been told the store manager is not available. I even called the headoffice and they told me they couldn't get hold of the store after being out on hold for a long time.