Blocking of number

I have transferred from contract to prepaid about 6 months back and I've using it without any trouble since then, but now cell c starts sending me sms's that my sim card is not rica'd and it will be cut off if i don't rica, i received 200 of these sms's in one hour, not only is this annoying but also i cannot make phone calls as it tells me i need to rica, people cannot call me and i cannot use the internet on my phone. I called the call centre many times and each time they transferred me to this person and that person and then they told me on their system my sim is rica'd and they don't know what the problem is. This sim was rica'd when i initially bought it and contracts are not given unless rica requirements are met.