Hello Marian, this is not an isolated case and all retailers on a lease will be having similar concerns. The reality is, is that landlords will continue to need tenants when the crisis has passed. It is far more efficient for landlords to hold onto current tenants than look to find new ones. Hence your client is perhaps not in as bad a situation as she/he thinks. In the initial instance I would recommend your client continues to discuss the situation with their landlord and seek a further lease holiday. Radnor may come back and agree to this on the basis that your client pays an increased leased in the future when the business is back on their feet.
As an aside, it is starting to appear we are getting on top of CV19 and it may be just a matter of weeks now before level 4 is lifted so encourage your client to hang in there and reach out to MBIE to understand other ways they maybe supporting businesses.