No vodacom signal

I recently got a vodacom Sim only data contract. At first I had poor reception and I thought it was due to the fact that I had just moved to a new area. Soon I had no signal at all, but then I found out that people who have pre-paid Sim cards have 4G network in the same area where I was failing to get reception. I called customer care and they said the problem is my device. I changed devices several times, I even use my brother's phone which had a 4G connection immediately before I changed the Sim card. When I inserted my Sim card the network became intermittent at best. At this point I believe Vodacom sells us these data contracts and then limits the signal so that we cannot use the data we paid for. It's really unfair practice on their behalf as I can't be paying for data that I can't use.