Very poor service and product!

This company has taken my loyalty as a customer for granted. I pay ove r500 f0r my wifi monthly but I have to still go and purchase data worth of over R300 because half of the time my wifi is connected but without internet. All tehy will tell me if to try shifting it around the house but the wifi works perfectly fine in the morning and in the evening when I have to start working the wifi suddenly is connected but without internet. I am not sure what kind of sevice company does this and then still expect that i can commit to extending business with them especially now that the prices are increasing, what exactly will I be paying for?.