Money not reflecting

I am very disappointed with Mukuru as a payment service. I had to pay someone an amount and paid a small amount initially, using the exact details as specified in the SMS that Mukuru sent to that person. She received the money, so I proceeded and paid the rest of the amount, which she never received. I used the exact same reference and details. Now there are a million excuses for why the money never appeared on her side, including that the reference is incorrect. I used the details sent by Mukuru, and the exact same ones I used for the smaller amount, which she did receive. Can someone contact me immediately to sort this out and pay the second amount?