Poor service

My mom was admitted November 2024 for 5 days for Operation, after discharged she wanted to claim for her hospital plan that she was paying and at hospital they refused to put a hospital stamp on the discharge letter so that she can be able to claim. The insurance declined the claim because they need hospital Stamp, is been 2 months now she's going up and down asking just for a hospital stamp to proof that she was admitted but they refuse. At help desk they don't even wear their name badges and you can't even tel who you talking to,You're assistant wil be much appreciated.