Created a new account to use the code SAVE15. Order confirmed but got cancelled in 5 minutes. Talked to Olive and was advised that each person has a unique Shopper Identification number. We're not allowed to create a new account for online shopping. I failed to see that from their Ts & Cs but this is how it works now.
After that, I also tried:
An order without using the code - cancelled
Another new account with a different delivery address and a different cellphone number - cancelled
In the end, I had to create a new account under my wife's name and use a different card.
Thanks for the heads up.