HP India — delivery of refill cylinder

As per information, delivery of cylinder is to be made within 7 days of receipt. I want to know whether we are suppose to remain at home for 7 days.
Why it cannot be delivered on the same day or next day.
After booking we are getting receipt no next day but delivery takes time. If there is any problem in delivery why you are making hurry in giving receipt and unnecessary keeping us waiting for 7days