Buying Voyager Miles with Greenbacks can be risky

On 4 March I was notified via SMS that my purchase of Voyager miles with Greenbacks had been processed. My Voyager account has, to date, not been updated with these. I have called the Nedbank Contact Centre 4 times to resolve it and every time I was told it has been escalated. My first call was on 17 March. Nedbank has acknowledged it is a system error and that they need to fix it, yet nothing appears to be done between my follow up calls. As far as I'm aware, this is a breach of contract as they have debited my Greenbacks but not credited my Voyager miles within the stated period. I stand to lose Voyager miles at the end of this month, at which time this 'system error' will cost me money.