Unexpected High Cost Wrist Guard for my own expense !

My wife went to Randburg Medicross for a sprained wrist. After the X-Rays, someone came along , said "Sign Here" and started fitting her with a wrist guard. The guard was clearly too big, and I had to convince the assistant to supply a smaller size, which fitted better. 3 weeks later, I was notified by my medical aid that this item is not covered by them and I have to pay the item in full myself - R1031.00 (which is R200 more than the medical aid rate). It would have been common courtesy to warn me that Medical Aid might not cover the item, and of the high cost. A suitable equivalent from any of the medical chain retailers would have been under R200.