What SecureIdentity look for is a well establish credible credit and financial foot print that link your Name to the Address you have provided.
Have you changed your Name or Address recently? less than 90 days?
Any Identity provider is trying to ascertain that you are Alive, a Real person and you are who you say you are,. This is a UK government stipulation to deter any attempt of online identity fraud.
Your best option is to try to Verify using one of the other certified providers, please see list below:
3. Experian (does not require a mobile device)
4. Post Office (can also Verify EU Citizens)
Alternatively, you can contact the government department direct for the service you require, stating that you were not able to verify online.