UNABLE TO USE DISCOVERY MILES

We have DIscovery miles and we wished to purchase items on Takelot.com. We have been trying to use them since 29 November and were unsuccessful. We had to wait until Monday to speak to somebody at DIscovery. Nobody has been able to tell us why we cannot use the miles, so we have missed out on several discounts. We have called in several times but nobody is able to give us a straight answer. We contacted both DIscovery and Takealot and have been pushed from pillar to post as neither companies wants to assume responsibility for the problem. All i want is a straight answer.