Surname issue

I have been having an issue with my surname and having it corrected by the bank. My Surnames on my ID are Ponono-Ncapayi and when I opened the bank account I gave them my ID 6yrs ago when I opened the bank account. They are having an issue with putting the hifan in between the last names and they have told me numerous times that they cannot fix this as their system does not allow them. This is an issue for me because it is stopping me from getting serious issues resolved and I have been wasting money going to different branches for the same thing