Cell C no roaming for prepaid

I activated international roaming before leaving South Africa and received an sms to confirm it was activated. When I landed in London it was not working, not calls data or sms. I need the sms for my banking and am in a bad position now because of this. I tried calling the customer service 3times and sent 2 emails but they are not understanding the problem and completely unhelpful. The first gave me a code to type into my dialer then refused to standby for me to try it on the phone and when I tried it did not work. The second told me I should have activated it 3 days before leaving and was being very rude blaming me and not listening. The 3rd would not help me at all because I got a security question wrong which I dont see how that is possible, I believe she didn't know the solution and wanted to get rid of me. Someone from cell c also told me to download the app which I did but it has nothing to do with roaming. I am on prepaid and now heard on fb they do not allow roaming for prepaid but nobody from cell c told me this and it says this nowhere on the website. I want to warn people if you are traveling soon, and are on cell c prepaid, be aware that you are going to be left stranded.