Poor service because discovery’s department don’t understand procedures between each other

Why are discoveries internal department miscommunications my problem? I requested an updat of Banking details as a service provider and as required personally delivered documents to them. I was told I would be contacted within 5-7 days to confirm details before updating their system. This was fine, they contacted me at times on one day when I was unable to answer my phone and later sent an email for me to contact them. On contacting them I was told that they need to call me and I needed to please advise suitable times which I did... 1 week later and no response from Discovery. This then results in me making multiple calls to them and each time I do supplying them with times I will be available to speak with them. Again I never hear back. Finally I am told by one of their call centre agents that they have a misunderstanding between their call centre and back office with regards to the process and so all the calls I have been making have been in vein as my initial case was closed and in order to have my request completed a new one needed to be loaded. I now have to wait a further 5-7 working days before someone will call me (probably when I can’t talk to them) to have the details updated! I’m not sure why I have to suffer due to your internal department miscommunication and lack of understanding between policies within your company!