Struggling to get death cover payed out

My mother had death cover with them. When she passed away 28 Jan 2021 i contacted them and sent all the documents they requested, then they informed me that i would have to provide a Letter of Authority before they can do payment. Struggled for 2 years to finally get the Letter. Sent the letter through to them on the 28th Feb 2023, and phoned to make sure they received it. Now i have been waiting since then for the payment to be approved,even with numerous phone calls. They moved over to new system so everything needs to put on for them to continue,on the 3de of April 2023 afer phoning again consultant tells me it through to pament department should be handled off by Wednesday. Phoned again today 6 April 2023 now consultant tells me it with financial department and can take up to 5 - 7 working days to get back for approval. Each time its a new excuse of why it has not been payed out.