Insisting I do a sim swop to keep my number

An individual Named Andrew and another he conferred with at the back insist I do a sim swop to activate my sim card after I migrated my contract from a fixed term to a pay as you go contract. When I did the migration this was not told to me only after I complained that my sim had been locked for some reason did they then indicate that I needed to do a sim swop for R200 to keep my number and to activate my sim card. My original fixed term contact was active for 4 years.<br> All I want is for my original sim to be activated in the present pay as you go contract