Pure incompetence

I have never come across such an *********** company in my life. Trying to contact them is almost impossible and makes my blood boil. I need to blacklist a phone. I am told I need to speak to the prepaid dept. I get put through and a message is read stating “we are unable to transfer your call right now, please try again later”. I phone the call centre back. They try and get through but with the same message. All they can do for me is report it to management and wait. No one can help me with the blacklisting in the meantime!!!! What type of service provider is this?! Why is it always so difficult to do anything with this company?!