It's really hard, but your Mum's care home is doing exactly the same as my Mum's home (and others) in terms of restricting all family visits. Vulnerable people have to be protected from the virus so it's understandable that only staff are being given access to the residents at this time but restrictions will be regularly reviewed dependant on government advice. Try to separate your previous problems with the manager from what action is being taken now to ensure that all residents and staff are being kept safe, which will apply to the families of all of the other residents there too, it isn't personal. Are you in contact with any of the other relatives? Since the restrictions started I've had text contact with another relative whose Dad is in the same unit as Mum and it has helped a bit to chat with someone who is going through the same thing at the moment, plus you'll find lots of people on this forum who know exactly how you are feeling and can offer support.
My Mum also loves close contact and touch - hand holding and a cuddle - and although she can't really communicate much now she does know my voice. A video call can't replicate a visit in terms of physical closeness but although Mum wasn't looking at me she recognised my voice and just being able to see her gave me reassurance that she was doing ok and was being looked after by the staff. I'm just trying to focus on getting through the current situation and hoping that things will get better in time so that contact with Mum will improve. I was worried that a video call would confuse or upset Mum but we both benefitted from the short call and it was really reassuring for me, so it's worth giving it a go to see if it helps you and is comforting to your Mum to hear your voice. Keep posting as there are others here who are in the same boat and struggling with the sudden changes to 'normality' caused by the virus. You're not on your own.