Discovery Vitality Flight Booster not paid

I activated a flight booster for a return flight in August 2019. According to the benefit, I would have been paid on 8 October 2019.

Unfortunately, after numerous calls and logging enquires, I have still not been paid.

The reasons are different every time and also the team responsible. At one point it was even referred to Vitality Money that has no link to this.

How do I go about to have this payment made, as well as the interest earned from 8 October?