Selling bricks which one does not own

Q: If I don’t have stock in my business, can I sell the goods? For example, a client comes and purchases a load of bricks and wants it delivered to his house. He pays us for the bricks and delivery, and though we don’t have it in stock, we accept the money. We then collect the bricks from the brick manufacturer and deliver it directly to the client’s house. Is this permissible?

Working out the price of the car after ascertaining how the client wishes to pay

Q: I am a car dealer. I am not involved in finance. However, I accept different forms of payment, such as cash, EFT and via a card machine. Is it permissible for me to decide the price of a vehicle depending on the customer’s form of payment? The bank charges me 3,25% (for a credit card) and 1,75% (for a debit card) of the total amount if the card machine is used. Can I add this percentage onto the original price of the vehicle? If so, does it have to be the exact amount the bank charges me or can I round off or add to the amount as I desire?

Error in the supplier’s calculation

Q: I do accounts for a certain person. Recently, a situation arose where according to my books, we owed a supplier R100 (for example), but according to the supplier, we only owed him R50. The reason for the difference is that the supplier made a mistake in his calculation. I pointed this out to my employer but he still chose to remain quiet. What should I do?