Dear Sir/Madam;
I recently received in the mail from your company, a __(type of item)__ that was accompanied by an Invoice in the amount of __($amount)__. Since I neither ordered this item nor require it, I have no intention of paying for it.
If you wish to recover this property, please contact me at __(address/phone #)__ to arrange a mutually convenient time for someone from your company to pick it up. Please be aware that I do not wish to receive any more unsolicited goods from your company.
Yours truly,