Insurance company say they're not paying out as my dads time of death is in dispute : LegalAdviceUK

In my dad's place of work they have insurance that covers a scenario where if the employee dies whilst having a child under the age of 18 then that child will receive £100k and the remaining balance of the mortgage paid off so the child and his mother can live in the property free of any mortgage.

My dad died in January this year, the time of death was documented to be at 10:58 PM. I would have been turning 18 just an hour and 2 minutes later. So when my dad officially passed I was under 18 and was eligible for the financial assistance package above. Or so I thought.

After putting in the claim via his employer my mother was told to get a death certificate, my birth certificate and a final balance on the mortgage from Lloyds and send it directly to the insurance.

2 weeks passed before we got a response from the insurance saying they're passing all the information on to their medical underwriters for a second opinion and have requested my dad's medical records. A whole month later they told us that they were seeking expert opinion from "multiple medical 3rd parties" and had put the claim on hold.

Today almost 4 months on from the last letter from the insurance we received huge 235 page report via courier which in short says that the insurance would not be paying out any money as my dads time of death is disputed and that he could have had a heart rhythm for at least 2 hours after his death. The insurance says the claim is only valid if the patient is asystole and as there's no proof of that it's conceivable that my dad lived beyond my 18th birthday.

Me and my mum don't really understand all the jargon in these documents and simple Google searches aren't really helping as I haven't been able to find anything like this ever happening.

What can we do here? Are there lawyers who can help us with this?