Vodacom And Sim card Expiry dates

Iv had the same telephone number for the.past 15yrs plus,my telephone was ****** and I had the run around trying to replace it,which I advised vodacom,their answer was that my number was allocated to someone else as i hadn't used my Sim card,despite relating the issue to them,Then several months later on checking up on my number *** it had been re allocated.All being well iv recently checked again and the number is no longer in use.Im unable to speak to an agent with the regards of trying to retrieve my number,which by this time I have lost lots of business clientele finances have suffered and loss of family and friends contact details.My question is how do vodacom maintain their clients if your number has an expiry date????How can I retrieve the number as it is no longer in use anyway.Lastly correspondence or trying to speak to a consultant is like looking for a needle in a haystack.Or alternatively they tell you a technician will call you back,which never happens!!!! A number that is most valuable to a business,where is the logic?