Vodacom sim swap

i am not happy with the service I received from vodacom. i have my sim card however i have changed phones and need the sim card to be a nano. i have visited a vodacom branch and they require 5 numbers that i last dialed. i was only able to provide 3 numbers as those are the numbers i call. i also had my id with me but nothing. now i have received a call from vodacom and i am told i need to get an affidavit to get the sim swap done. i dont understand what i need with a affidavit as i have my id and i have the sim card and i am there in person. is it so wrong to wanna do the right thing and get a sim swap done?