I ported from Vodacom about a year ago, lured by an awesome deal and great rates. Boy did I make a mistake! I've since found that Cell C's data network is horrible. Don't be fooled when they claim 90% or however much coverage, coverage is not the problem. It's the quality of the coverage that's the problem. The areas where a would like to use data are Somerset West (Fernwood est), Kleinmond and Tulbagh. In Fernwood estate I have neither voice nor data coverage. In Kleinmond I have the worst data coverage.
I'll be porting back as soon as my contract is done.