Nu Debt Management frustration

I paid up my debt with previous provider. Now i just cant call Nu Debt Management. The 0861 nr answers. It says Sales - 1, Queries-2, Make a payment - 3, Operator - 4.

I went through all options & then just silence. It doesn't ring, it doesn't state u are on hold. Nothing.

Please can you call me urgently on the number listed by you. My ref is ND***5