Options for Cell C Contract Cancellation

Hi
Not sure if anyone can advise i have a cell c contract, 7 months old on the iphone 5, ported from vodacom to get this contract and given all the problems on their network i really cant take it anymore

• i miss nearly 80% or my calls, most of them going directly to voicemail
• i drop nearly 80% of my calls, and finally give up trying to contact anyone
• don't have any data connection that provides speeds that's usable

given all of this, being on cell c is costing me more than its worth

so would like to cancel with either the following option

1. Cancel with buying the phone , not sure if penalties will apply , so that i can port back on prepaid
2. or just return everything back incl phone, not sure if this is possible

please can anyone advise if they where successful