Failing to Debit from account

I changed my bank details but Old mutual keeps on failing to debit from the new account this is happening for a second moth and its not right cause next thing a claim will be done ad they will be quick to tell me that my policies are not up to date. I have had these policies for more than 5 years and I am not willing to let them lapse due to Old Mutual slow system. I called old mutual to address the issue but the person who I was speaking to said they cant log into my policies to check.