Not registered on network

I've been an ID customer for about 3 years, after about 18 months I started to have some issues with mobile data (being unable to connect to 4G, having to restart phone 3 times to use data for about 10 minutes before it went again) but was told this was because of the handset/poor signal. I upgraded at the end of my contract and the problems persisted. I called up and was issued a new SIM card which had the same problems as the first. I went into carphone warehouse and they said that a new SIM card wouldn't make a difference and that I had to call ID and tell them to reset the network on my account. I spoke to ID and was told that all they could do was send me a new SIM card. Again this had the same issues with data but over the past couple of weeks it's started to lose connection to the network full stop. It's always emergency calls only I cannot send or receive texts or calls. Occasionally if I restart my handset 6 or 7 times in a row I can connect to the network for a few hours then it goes again. If I manually connect to the network it says 'unable to connect try again later'. I live with my partner and his ID mobile works perfectly so I know it isn't a problem with the area and I've tried my SIM card in several phones to test and it's always the same (currently using a Samsung s6). I cannot call ID because of my network issues and the live chat is always down so I'm unsure about what to do next.