Disabled customer request for wheelchair

Booked a flight 8th Feb to fly 12th Feb to Port Elizabeth and requested WCHR wheelchair for 72yr old husband who suffers COPD and cannot walk far. I stared in my vety first email request on the 8th that he can climb stairs but was still asked to advise if he can climb stairs etc. Subsequent emails followed and eventually your Penny Smith rep**** we are within 7 days of flight ??and must book another as no wheelchair available. I requested her to refer my request but she did not even bother to reply back, not even an apology. We already booked an Uber to pick us up, paid for, and could not change flights at the last minute. At the airport we spoke to Nduduzo at your service desk who was friendly but did not make any effort to try and assist us. My husband had to walk all the way to gate C10 carrying his portable machine. He was obviously out of breath. On the way and at the boarding gate we saw many empty wheelchairs. Surely someone could have assisted us but no effort was made by any Safair staff. This makes me question the care that you display towards disabled customers. Very disappointing