Poor service

Firstly we had a problem with our router kept on switching off which it was last year. So I called a technician was dispatched came to the house to help he switches the routers which we thought it had a problem only to find out the ups had a problem, so now he gave us a smaller router the rage is totally bad in some parts of the house we can't connect called them and explained the router you gave us is smaller then older. I was told to buy an extender why if the old router was connecting perfectly nomatter where you stand in the house. We requested them to bring back our old router they didn't want to bring if it was a matter of collecting it's still fine because we realized that the router they took was working for sure the technician picked that up and still switched the router. A friend whose a technician at his own work place came to help, he just removed the ups and said 100 % sure that router they took was fine it was a ups which had a problem not the router so basically i feel ****** straight because you guys clearly took back your router thinking you smart. Now I'm trying to go on Google to pay for the internet we doesn't allow me I'm calling the whole day I'm struggling to get help I'm told to hold the line for 20 minutes I have no internet in the housebi have work to do I just want pay no one is bothering themselves to at least tell me what's going on tried downloading that stupid app it doesn't want my password tried changing it still doesn't expect it. I don't know what to do but just remove the whole thing and get a new service provider because clearly the service from metro fibre is nonsense