Endowment policies can indeed be ceded and there are investors who usually do buy these policies. Problem is, as mentioned, some companies do not allow this. You need to get a copy of your agreement and see if it is allowed. Investors are very picky on what they buy and you will often get less than 10% of the value of the policy (around 1-3%). If it is very close to maturity, you may get more (probably around 5-6% of the value, if that much).
The biggest problem today is that there are very few buyers left in South Africa. In fact, I will not be surprised if you will not be finding a buyer at all. Since the introduction of Capital Gains Tax, most these investors dissappeared from SA and is now making a living from this abroad.