Cashback still not received

I contacted Discovery on 1 November to ask how my cashback was calculated because the amount I received was far below what I knew it should have been. On 5 November Discovery Vitality confirmed that only the Vitality portion of the cashback was paid and that they would refer the Discovery Bank portion (on Vitality Money) to them to resolve. Apart from a couple of emails asking when I could expect an answer and subsequent apologies that it was still in process, I still have not received my full cashback or an explanation as to why it takes so long to pay me (for an item bought early in October at Sportsmans Warehouse).