Can't port number I've had for 15 years to my new Vodacom contract

I don't even know where to start. I've had a cellphone number for around 15 years, I was originally with Vodacom but have moved over to other network providers in the 15 years. Late last year when I realised my contract was coming to an end with Telkom I decided I was going to move back to Vodacom as I thought Vodacom was the best network provider. My contract with Telkom ended on 9 January 2019 and I got the new contract with Vodacom on 19 December 2018, if I can recall correctly. Today I decided that now that my Telkom contract ended and my number has moved to prepaid I will move it over to Vodacom. I first called the customer care line and they said that I will have to go in store to port the number, when I went into the Vodacom store in Midstream they told me that it was impossible to port my number now on Telkom prepaid to my existing Vodacom contract, and the only way was to get another Vodacom contract, that instantly ruined my day!!!! I decided to call customer care again and they gave me the same story, I can't port my number to the existing contract I have with Vodacom. How on earth is that impossible in the year 2019?? I then asked to talk to the team at Vodacom porting, the lady there told me that I can get an additional sim card and port my number to that sim card. I recently wanted to get an additional sim card for my data top up contract but the same lady at the same store told me that I can't have multiple sims on my contract. I am very confused with what I need to do, 2 years ago I went through the same process with Telkom and I had a seamless port with no problems. If I can't keep my number I will have to cancel my Contract and if I need to pay a penalty I will have to look at legal action. Nobody ever told me that I won't be able to port a number if I get a contract with Vodacom and then decide afterwards to port my number. I ask you kindly to assist me in any way possible to keep my number with the contract I got with Vodacom.