Standard bank payment scheme

So Iv been call and put on a payment plan or holiday during the lockdown, however Iv been once again disappointed by standard bank no emails no sms's no calls to state that the payment plan has not been lodged correctly or Iv missed payments to my surprise Iv received a letter of demand how the hell!!! And when phoning to standard bank they don't have any decency to call you back or whatsoever I want my issue resolve how the ****ed can you just get a letter of demand out of no where super frustrated