Number has been cancelled after 16 years! After I asked in writing for retention to prepaid!

On the 13th of January I completed all the relevant form at the Vodashop in Vredenburg, where a very kind lady assisted me, and even copied me in the correspondence mails where it was explicitly asked to cancel the contract but retain the number on prepaid, as I have plans to port to another SP. Since sunday I have not received any phone calls which was not much out of the ordinary, but when I realized no call has been received by monday 12 o clock, I started investigating, and surely when my number is dialed, the call is immediately dropped. I tried calling vodacom, but they transfer me from one dept. to the other. This is unacceptable and not the kind of service I expected from a SP whom I've been with for over 16 years!