Mortgage Changed from Flexi Option with NO Notice, NO Warning and now I must reapply?

I have had an FNB Flexi Option Mortgage with FNB for 4.5 years now and use the Flexi Option on a regular basis and the account has always been in good standing. Last week I transferred a large amount of money to the Flexi Option Mortgage but, when I logged into my account today it is not available. I have called the call centre (no special treatment for long standing Platinum Account Holders there) and been pushed from pillar to post before finally being told I have to apply to get my Flexi Option reinstated and then being cut off when I asked to speak to a manager. FNB, you call me, you explain WHY you have changed my account without notifying me and you give me access to my funds please.