Bad service and assistance from travel agency

My wife is visually impaired , we booked airline ticket and hotel accommodation through corporate travel agency. They also assisted her with her visum. The day she arrived at the airport she was told that het visum is for a day later than the day she was booked to travel. unable to see she called the agent to try to resolve this, the agent that assisted her was unavailable, another agent told het that she needs to cancel her flights in order to book new flights. In doing so she lost the money for her booking and had to pay again R20000 for her new flight. She also lost al the money from the Hotel were she was booked in. She now must take a later return flight , and must now book extra accommodation at the hotel. Al off this could have been prevented if the agent checked everything properly. My wife is visually impaired and can't read al documentation, that Is the reason for using a travel agency. She lost lost all the money of her first flight booking and half of the Hotel booking.