Section 427. Buyer's or other obligor's right to cancel

1. In addition to
  any right otherwise to revoke  an  offer,  the  buyer  or  other  person
  obligated  for  any part of the purchase price may cancel a door-to-door
  sale until midnight of the third business day, or until midnight of  the
  seventh  business  day  in the case of a door-to-door sale of a personal
  emergency response service, after the day on which the buyer has  signed
  an agreement or offer to purchase relating to such sale.
    2. Cancellation occurs when written notice of cancellation is given to
  the seller.
    3.  Notice  of  cancellation,  if given by mail, shall be deemed given
  when deposited in a mailbox properly addressed and postage prepaid.
    4. Notice of cancellation need not take the form prescribed and  shall
  be  sufficient  if  it  indicates  the  intention of the buyer not to be
  bound.