Poor Service Delivery and Clerical/Administrative Service

For over 3 months I have been in the process of claiming my cellphone insurance with Vodacom Cellsure with the assistance (or lack thereof) of Vodacom Alisom Cycad. The Sales Consultants who assisted me with the update of my insurance in 2019 have failed to properly record the update, now the insurer claims that without the relevant documentation,which I submitted in store, the claim will be rejected. How am I held liable for their staff's incompetency? Now the person does not even work at the store anymore and they have stopped taking my calls, when I go in store there is always an excuse and they will claim that they will call me, which they have not done in the past week or 2.