Business and Dealings

Father buying from son who is a rep

Q: My father is the buyer in the shop  

3 reps come:

Rep A offers R 2.00

Rep B offers R3.00

Rep C offers R3.50

Can my father accepts rep A offer although it is his son. In the shop my parents told me 90- 98 % of the time they do not send people to go and buy. They get their goods from reps who deliver. So by selling to them I am the cheapest rep (where I buy from is cheaper, they know of this place, but they do not buy in that manner 90-98% of the time). So now what I am doing is it permissible?

Charging to do an EFT for someone

Q: A friend of mine needed an eft into his account for a million rand to avoid bank charges and he would give me cash. I told him it is going to cost me couple of calls and petrol and I would charge him 5000 rand for my troubles. Is the 5000 rand halaal for me. If not then in future how do I structure these kind of deals?

Credit Cards

Q: Most credit cards have a facility where a person is allowed to use credit up to a certain amount and if it is paid back to the back within 55 or 60 days etc then no interest is charged, however from the onset the client and the bank are fully aware that if the client fails to pay within that time limit then interest will be charged. Is it jaiz for the client to utilize this facility and pay in the money within the time limit?