FREE GIG BUT NO INTERNET

I am so disappointed in Afrihost. My 2 sons, my husband, and my neighbour are all on Afrihost Mobile which I recommended to them! Only to find now that MY free Gig every month means nothing! As soon as I am off WiFi I don't have internet. I've checked and re-checked the APN's which I can do with closed eyes already, and which is precisely what the support tells me to do. I even have the step-by-step instructions sent to me. Sometimes, after I'm assisted by support (like 4 days ago!) it works fine, only to go offline again. And so it goes..... Totally frustrating!