US Periodicals Misleading "Offer" sent in billing statement form to my 86 year old mother Phoenix, Arizona

My 86 year old mother received a magazine "offer" in the mail from US Periodicals titled "Billing Statement" which included a minimum payment due and a due date for a subscription for TV Guide.  Naturally, she thought it was a bill the she was responsible for paying.  Since she already had several years of TV Guide, I contacted them to cancel and request a refund.  The customer service supervisor "Jake" said it was already processed and refused to refund her money. 

I complained about the form of the "offer" as a billing statement and stated that it was very misleading, especially to elderly people who have difficulty with their memory.  Jake responded that the post office approves their mailings and they don't know how old the person is who receives it.  I told him she could not afford the subscription on her fixed income and asked again that it be refunded.  He said he wasn't going to argue with me and hung up.