Moved from 5G to 4G

I'm paying offer for 5G but I have been moved to 4G and the network is very bad, in such a way that I can't even do my studies, or steam, I called customer service NO one seems to know why, i have been told to switch off the router for 10 to 15 min, and the matter will be escalated, No one call me me back, the speed you have to remind me about the payment or terminate service, can this get the same speed to be get resolved.