Non-service from business bankers

Our business received a strangely worded email that did not make sense, but placed restrictive control on our accounts. We have tried to contact the assigned business banker- but she has not returned any emails and did not answer the phone. I phoned the call centre for the 2nd time, only to find out that seemingly our bank mandate, operational since November 2020, has disappeared overnight and defaulted to the old signatories. This has left the organisation without recourse to correct this problem and we can't access the funds in our accounts.