TELKOM MOBILE NOT CANCELLING CONTRACT

About one and a half months ago I went in to Telkom Mobile in Wonderpark and requested them to cancel my contact. The guy helping me indicated that the request was made. I made this request, because my contract period was going to expire and I wanted to change it to pre-paid. When I requested him whether there is any documents that must be completed to signed, he indicated that it is not necessary. Now today I realised they never stopped my contract and when I contacted them they told me there is forms that must be completed and it will take 21 days for them to send me the forms. Please with immediate effect cancel my contract.