unjustly declined

I was referred for this esophageal manometry for the 15 February 2017. at Dr JF Botha 302 Sandton Medi-Clinic, Bryanston. I obtained an authorisation number from Thebemed Reference no ********** 84 spoke to a lady by the name of Pam. After the procedure was done, consulted with Dr Botha. Yvonne the secretary informed us that the bill will be emailed or sent to us via post. Nothing was received or sent. We checked our junk emails - nothing was received. In the interim we moved residence. No mail was sent to our old address and neither to our email address. Not hearing anything from the doctors rooms, until the debt collector contacted us. The doctors rooms had all our information such as cell numbers and work numbers as well as our residential address and email address. After when the debt collector contacted us. I then contacted Thebemed and was told to by Zandile to email the invoice to ********** which I did 6 November 2017. Thereafter I kept informing the debt collector as well as Yvonne at Dr Botha's rooms on the progress of the claim. Only to be told that the claim has been declined due because it's over 120 days. As I feel this has been unjustly done. Then why have a stale claims department and me having to get an authorisation number to be turned down at the end of the day. I feel that the doctors rooms should have contacted us within a reasonable time, which they never did.