Extra service fee and airtime being depleted

On Sunday 05/05/2019, I deposited money in to my FNB gold cheque account and to my surprise I was charged a service fee of R8.55. I tried phoning FNB to query. My first call the lady kept saying she could not hear me and so I cut the call, second attempt I spoke to someone, had to verify my ID number despite being put when prompted by the voice command. After giving my ID number the call had got cut on it's own. My third attempt the lady told me all systems were offline. I have an FNB sim and I was told all calls to FNB (call centers) were free so how did my airtime manage do get depleted? The number I dialed was ********** . Why was I charged service fee to do a cash deposit when clearly I had not deposited more than R5000 in my account?