HUF

If the kartha (my aged father/79)of a huf account is due to ill health cannot regularly operate day to day cheque signing etc, in that case can kartha appoint his "mandate holder" or letter/power of authority holder? Particularly to operate the bank account? Because the bank is refusing to give that facility saying that only kartha has to operate on a day to day basis...and there cannot be a mandate holder for huf bank accounts..... Can any one help with any remedy/ solution?? With kind regards Smehta