heart attack 😣

Hi I'm looking for advice from UK citizens. my father in law is a fairly unwell man and since having a near fatal blood clot a few years back has to take blood thinners, due to being unable to get about easily his prescriptions are delivered to him. Sunday just gone he had a massive heart attack because his main artery was blocked. He's had two stents put in and is very lucky to be able to tell the tale. We found out that they haven't been delivering his blood thinners to him which seems to have been the cause of the heart attack. They said they would deliver them to his address the Monday just gone, he's got home from hospital this evening and still no medications have arrived or been left with who he lives with as instructed. He has the confirmation messages on his phone to prove they said they would get them to him ready for his return home. What happens now?! Is this a legal matter as he could of died due to their negligence? Thank you