Overpriced "rip-off" costs from ER24

On 29 March 2019 my Mother fell and broke her hip and had to be transported via ER24 ambulance from the Frailcare centre where she lived at to the Life Flora Clinic, only about 4 km away. She underwent surgery and had a hip replacement.

She was released from hospital on 25 April 2019 and had to be transported via ambulance from the Life Hospital back to the Frailcare centre. We were informed that the medical aid would not carry the additional cost and we there had to pay for the ambulance in cash. This was done and an amount was R900.00 was paid in cash to the ambulance driver.

An account was later submitted by ER24 stated that an amount of R5 755.00 is owing for the first ambulance trip from Frailcare centre to Life Hospital. I queried this huge amount and was told it is correct. My complaint is that the return trip only cost R900.00 whereas the first trip cost R5 755.00. Is this possible? Both trips only involved a distance of about 4km. Why the huge difference in cost?