Good to talk to you.
1. There is a failure to provide any service whatsoever - which is a breach of contractual obligation
2. With no regular reviews, even by telephone - a breach of relevant care regulations
3. Possible negligence in a failure to act/ support esp given the recent additional diagnosis
You have grounds to withhold payment, but set aside monies in case the decision goes against you so you are not out of pocket if ordered to pay. You have to put this in writing in a complaint which you have done today.
You have a legal case on the above points, but legal action can be slow, time consuming in itself and costly.
Your MP should be your next point of call, it's a local issue and a human rights issue - everyone appreciates Covid-19 has put all services under pressure but as the leaflet you received states, there should be alternative means of support being put in place. You've had nothing at all and your family is suffering as a result.
I would also question why respite care from LA carers is not being provided now. It's a vital service for your family.