FNB ******* elapsed Life cover.

In 2018 I took Life cover policy with FNB and I was paying my premiums via debit order each and every month with no fail as I was banking with them for a long time .Then FNB changed my cheque account into Premium account ,then in 2021 I became a breadwinner in our home and premium account was expensive. I just couldn't afford that account. I went to the branch to ask them to change premium to cheque account but to no avail. Then I decided to switch banks. I started looking for a bank that will charge me monthly fees that are cheaper and I found it. In October 2021 is when I started banking with the new bank. Then I sent an email to FNB with the new bank details requesting them to switch banks and let my life cover policy premiums paid via debit order of the new bank .I even called FNB to inform them about my decision. In first week of November FNB did not process the debit then I paid them myself. Following week FNB sent me a message informing me that my policy has elapsed. Are we not allowed to switch banks in SA? How about my money I have paid for all these years? Is it a sin to switch banks?