Activating Roaming whilst outside of SA

I have only been a MTN customer for a few months but I have had endless trouble. Apart from the high data costs and a recent price increase on my contract after only 5 months, which seems to be the norm for all South African service providers, I have to date never received one invoice yet abnormal amounts get deducted from my account. I have been trying to call customer care from outside the country just to be left on hold indefinitely. I travel a lot, mostly on short notice and on my most recent departure from South Africa I did not activate my roaming. I only return next month and urgently need roaming for banking purposes. When calling the store where I signed my contract I was told there is nothing they can do. I cannot believe that this is the case, I never had this problem with my previous service provider. Please can you confirm that once you leave the country MTN can do nothing to activate roaming. Or can you give me a direct number to call where a real live human being will actually answer the phone! Your assistance is greatly appreciated. Regards, a very frustrated MTN customer.