Siauer review: Unauthorized billing

Stauer;s billing department continues to send me bills of $21.55 for account number [protected] for an item shipped on 05/26/21. There is what they call a CTL# - [protected]. I have no form of credit with this company.
I have purchased perhaps at least a dozen items from Stauer over the past few years, and it has always been via credit card and paid in full at the time of the purchase. I have NEVER established any form of credit with Stauer. When I make a purchase they tell me over the phone what amount is due. I then give them credit card information, which they accept, give me a shipping number, and the item arrives some time latter. It is all very simple and clear. Now Stauer has continued to bill me at least 4 times. I have responded both via phone and by mail, but they will not give me the full details, or the reason for this supposed transaction charge.
All I have asked for is the afore mentioned information before sending them this small amount of money, but the request is completely ignored. Once again " all my transactions with Stauer have been paid for at time of purchase". Please advise
William Wetterer
[protected]@Yahoo.com
ph [protected]