No service to make calls or use internet

I've had my mobile for over a year now and can only use it for WhatsApp when connected to WiFi. If I make a call it cuts out within a minute or two. I've tried multiple times to get help to no avail. Even to ring my GP they cant hear me and I have to get my husband to ring back on my behalf. My phone bill shows I make zero phone calls and approx 98% of my data is rolled over every month cos I can't get internet to use it. Every time I get in touch with ID mobile they try to ask for more evidence etc but surely my bills showing zero use of internet and calls should be enough. I'm at the point of getting a second contract with Vodafone but can't afford it and shouldn't have to. Please help