Written Quotation doesn't match verbal agreement

My Mother visited an Absa branch to discuss further lending options for renovations. The consultant assured her that her current bond would stay untouched and that they'll calculate a new interest rate only on the further lending amount. My mother was satisfied with this deal - trusting the consultant who advised her. <br> <br> She signed the quotations. Only when the first monthly statement came did she realize that the interest rate on her current bond had not only increased, but that the loan term had been shortened with 10 years. She is now forced to pay way more than she can afford monthly. She phoned the bank and asked to please revert back to the old bond, that she'd repay the further lending amount immediately - they refused and said it was impossible because she signed the quotations. <br> <br> My Mother is nearing 60 and isn't good with terms and conditions, etc. She trusted the bank to advice her and walk her through the process / paperwork and to notify her of any changes to what they initially discussed face to face. Instead, they just asked her to sign with the secretary up front. My mother did so with no reason to suspect that the Bank was taking advantage of her. <br> <br> Is this ethical?