Vodacom signal

O have an mobile router from vodacom with 300 gb on it every month but i can’t use it as it never works. It wil work for few minutes and then there is connection lost or no signal. I pay for this service and it is not working properly. When i watch a movie on Netflix its buffering movie plays for a while then buffers again. When i listing to music on phone het also buffers alot. It use two work fine but the last 2 months this happening what is going on with your signal????