A waste of money on a data contract

I have a data contract with Vodacom that works via a wifi router. I got the contract so that the whole family can connect to the internet. The signal is so bad in Bonnievale that we can't use the data. So every month I pay we don't get to use the data, we end up having to buy mobile data - which works only slightly better. The signal indicator on the router is always green - indicating good strength, but it doesn't translate in to being able to use the internet. It is so frustrating.