"Unable to use service provided "

My relative is currently in stroke unit the sister has refused me access with my carers card saying I cannot use it. My dad suffers from very bad mental health and anxiety he is terrified of hospitals. He has always had me with him this is very hard experience for us as a family we have no communication from doctors or anyone only when my mum visits for the hour allotted to her. She is exhausted and cannot take a break as I am not able to take her place to give her a rest. I understand with covid they would be restrictions but this feels awful that for 23 hours a day my dad is on his own he won’t be used to this and this is the reason we applied for an emergency carers card in the first place. When we call up for an update we’re told well your in later anyway so find out then. We are so upset I would like information on how to make a formal complaint about all of this I do not feel we are being treated fairly and this can’t always keep being blamed on Covid.