Sim swap

I misplaced my prepaid sim card which I have been using for years now , so I called customer care for sim swap and I was adivsed to go to the store as I have not been using the sim for two months... I was advised the sim is still active and still under my name.

Now the store agent says I need to recall the 5 last dialled numbers or else the sim swap wont be possible and I obviously cant remember them. I even asked if maybe I can do an affidivit like they do with MTN but they said I should forget about my number.

I use the number for whatsapp as well so what happens when it gets recycled ?