Fionamarshall

I have registered with government gateway, received my ID and have been able to log in. However, when I enter my NI number it is not recognised even though it is correct. I tried to then enter my postcode, again correct, but I am told that it does not the information I have supplied. I have contacted digital support and received a response that was of zero use. Who or what do I contact to see what the issue is? I have already cleared caches and so forth on my device and tried other devices but no use.