Losing business due to Vodacom

Do not use Vodacom. I am losing business, Dropped Calls, Missed Calls, No Mobile Network, doesn't go onto messaging. All I want is for my Sim Only contract to be cancelled without penalty and have my sim migrated to prepaid so I can port to another Service Provider. Since 9 December I have been given 5 or 6 reference numbers, they get closed I am told problem fixed, or closed because they could not get hold of me. The problem is not fixed. Totally useless.