sim swap nightmare

i got ****** on saturday night , i contacted cell c for a sim swap, they asked me for 5 last dialled number which i feel is too much , i mean 3 numbers could be just as effective as a security measure, i was then asked my last recharge and how much data i last purchased i do not purchase data as i have fibre at home and most of my calls are done through whatsapp using that same fibre . i have been using this number for over ten years and i am unable to get assistance from cell c and it is ridiculous and appalling to say the least. i am unable to claim from my insurance as you guys will not blacklist my number without answering the same security questions. Your service is the worst