For the last few months I seem to have no coverage inside my house (in London!). It shows as 2 bars but if I try to make a call it doesn’t go through and incoming calls go through to voicemail. I have wifi calling enabled but that doesn’t seem to work either. It has been saying “we are working on your network at the moment” for the last few months under network status! 
I work from home so this is becoming a nightmare. Any advise on how I can actually speak to someone about this and get it resolved. I feel frustrated as tied into my contract until mid next year but am not being provided the service I pay for!