****MED! Discovery Bank / Vitality Active Rewards - iPhone Benefit?

I have observed that Discovery deducted the full amount from my credit card for the "iPhone Benefit" programme. Specifically, I noticed that the deducted amount is then transferred to a Budget account to fund a phone purchase. However, I am perplexed by the fact that this transfer seems to be using my own money and is accompanied by interest charges. I would greatly appreciate an explanation of this process to understand why my own funds are being utilized for this purpose and why interest charges are involved.

I value the relationship I have with Discovery and have always appreciated the services you provide. Therefore, it is important for me to fully comprehend the processes and policies that govern my credit card account, my own positive credit....and not Discovery's credit facilities. By clarifying these matters, you would not only address my concerns but also enhance my trust and satisfaction as a customer.

WARNING!! YOU WILL FUND YOUR OWN IPHONE WITH INTEREST if you accept this "benefit".

I kindly request that you provide a detailed written explanation of the following point: The process of deducting the full amount from my available funds and transferring it to the Budget account for the phone purchase, particularly why my own funds are being utilized and why interest charges apply.

Nowhere does it mention the customer is paying for the iPhone in FULL...with their own money...upfront....in a Budget Account to get the "benefit" of a cashback (0%, 17,5%, 25%, 50%, 100%)