Waiting months for a refund

Momentum incorrectly made a payment to me, in stead of to the Service Provider. They took so long to reverse the payment or to pay the Provider, that I paid the Provider on 31/1/2019. In the intern Momentum also paid the Service Provider. Then I was told they will reverse the payment from the service provider, and refund me. Every time I phone the Call Centre, or I query it via email, I was told unfortunately the process date was moved forward.... Last email was on 6/3/2019 - was told money will be in my account within 3 - 5 working days, but still not received. Today I phone, was told that refund was moved to the pay run of 25/3/2019.