Telkom Mobile let me down badly

I was urged by Telkom to upgrade my existing Telkom Mobile contracts. I have done so and asked that Telkom make sure my international roaming is activated again. I later phoned, waited a long time in a call center queue and was informed that roaming was activated on the two new contracts. When arriving at my international destination, I discovered that my roaming was not activated on either of the two accounts. This resulted in a crisis and I eventually lost an entire day of my holiday to find a way of communicating. Apart from this problem, how do I know in future I can believe what Telkom Mobile tells me??