New Sim Card a Total *******!!

I bought myself a new phone, but it takes a nano sim, and my old sim is a micro sim, so I bought a R3.99 sim from the shop, and tried to do a sim swop, only to be told by vodacom customer care that the "prepaid" sim cannot be used for contracts, and that a new sim card for contracts is anything between R65.00 and R200.00! I explained that I have had my contract since 2003, and have supported vodacom all these years, always up to date with payments etc etc, so why must I get ********** on anew sim card for my contract. The consultant didn't like what I was trying to explain to him, and he cut the call on me! Please vodacom, why must I pay such a huge amount for a new sim, when a pre-paid sim card is only R3.99??