American Musical Supply denied me because of someone elses dispute midland park, New Jersey

I ordered a guitar for my son for xmas this year. They refused to ship it, sell it to me or let me pay it out because they have a dispute over something with a relative of mine at the address i wanted it sent to. I did not ship to my house so my son would not see it. They refused to ship to any other address too. Called me a liar, said it was too late. that they already knew I was associated with someone they had a dispute with. Told me I could be buying it for someone they did not want to have it. Told me to tell my relative to settle their dispute. Called me a liar when i told them i did not know what they were talking about. It should not be legal for a company to deny me service because of a dispute with a relative. Especially when i have ordered from them several times in the past and have paid everything on time. I just wanted to order my son a xmas gift!!!!