Pahtetic service provider

All tough the network covarage here were I live is excellent (4G) the Price plans MTN has is useless. For years I am batteling with cell c's rubish coverage and whatsapp data. Now that MTN has launched theire whatsapp data I wanted to give it a try. Every time I wan't to purchase the data. I receive a message that it is not compatible with my other bundles. Whats the use if you launch a product witch is supposed to be beter than Cell C's rubish and I can't purchase it . And if you try to phone the customer don't care line you can't even speak to a agent. MTN is a useless and pathetic provider.