He is an agent for a company and he sells goods for a price higher than that of the company and keeps the extra amount
Question

                My father is an indenter. He is a sole agent in pakistan of a manufacturing company of Malaysia. Now, my father imports and sells. But some customer demand for the whole container of the product. So my father gives them an indent(proforma invoice of the Malaysian company).

But the prob is that my father always tells the customer the amount which is more than the amount offered by malaysia company.So the amount above goes into my father pocket.

I dont think this is halal for my father since he is not purchasing and then selling, rather he is just an agent. He can only be entitled to commission that the company might give to him per $ sold or per product sold.

I argued a lot with my father but he says that this is the practice done by everyone and that this time is different than the time of the Holy Prophet(Peace be upon him). please help me in making my father understand.
Praise be to Allah.
    This transaction may take three forms: 

    -1-

    If your father buys the product for himself from the 
    Malaysian company, then sells it to customers in Pakistan. 

    There is nothing dubious in this trade, and whatever he makes 
    of profit is his to keep; it has nothing to do with the price for which the 
    Malaysian company sold it. But it is nor permissible for him to tell the 
    purchaser of the price charged by the Malaysian company unless he is telling 
    the truth about it, in the sense that if any customer asks for the invoice 
    from the Malaysian company, or to tell him the price he bought it for from 
    them, then he works out a reasonable profit and offers him a price on that 
    basis, this comes under the heading of a transaction based on trust. It is 
    not permissible for him to tell him anything but the real price. 

    -2-

    If your father is simply an agent for this company, and 
    markets its products according to the prices set by the company in return 
    for commission that he takes from what he sells, or a fixed salary that he 
    takes from the company. 

    In this case, he does not have the right to sell to the 
    customers for a price other than that which is set by the company, and it is 
    not permissible to take the extra profit for himself, because that comes 
    under the heading of betrayal of the company that has appointed him as its 
    agent. It also involves cheating and deceit of the customers, because he 
    makes them think that this company’s products are being sold at the official 
    price, whereas that is not the case. Our Prophet Muhammad (blessings and 
    peace of Allah be upon him) said: “Whoever deceives us is not one of us.” 
    Narrated by Muslim, 101. 

    In al-Mawsoo‘ah al-Fiqhiyyah (45/42) it says: If the 
    one who appoints an agent sets out specific guidelines for him, he is 
    obliged to adhere to them when carrying out the task he has been appointed 
    to do on his behalf, according to the consensus of the fuqaha’. End quote. 

    In Fataawa al-Lajnah ad-Daa’imah (14/264) it says: The 
    agent is a trustee, so it is not permissible for him to take anything from 
    the price except with the permission of the one who appointed him as his 
    agent. If he allows that, then there is nothing wrong with it; if not, then 
    he must return the rest of the money to him. End quote. 

    The scholars of the Standing Committee for Issuing Fatwas 
    were asked about a man who was selling goods for another man, and this man 
    is adding to the price and keeping the extra amount for himself. What is the 
    ruling on the one who does that? 

    They replied:

    The one who is selling the goods is regarded as an agent of 
    the owner of the goods, and he is entrusted with them and their price. Hence 
    if he takes something of the price without the knowledge of the owner of the 
    goods, then he is betraying the trust and whatever he takes is haraam for 
    him.

    End quote. Fataawa al-Lajnah ad-Daa’imah, 14/274 

    See also the answers to questions no.
    9386 and
    98439.

    -3-

    If he is an agent for the company, but it has agreed with him 
    that if he sells for more than the set price, then he may keep the extra 
    amount. 

    In this case, the matter is the subject of a difference of 
    scholarly opinion; the more correct view is that there is nothing wrong with 
    it. 

    Ibn Quddaamah (may Allah have mercy on him) said: If he says: 
    Sell this garment for ten, and anything more than that is yours to keep, 
    that is valid and he is entitled to the extra amount… Ibn ‘Abbaas did not 
    see anything wrong with that. End quote. Al-Mughni, 5/108 

    Imam Ahmad was asked about someone who gave a garment to a 
    man and said: Sell it for such and such amount, and anything more than that 
    is yours to keep. He said: There is nothing wrong with it.

    End quote. Masaa’il al-Imam Ahmad wa Ishaaq ibn Raahawayh, 
    6/2566 

    See also the answer to question no.
    9386,
    121386

    And Allah knows best.