OP....not sure you are just worried that this guy has done his job properly and won't issue you a certificate that you need to go make money from your tennants.
If you are unsure he is qualified check him out on the gas safe register.....as for air bricks blocked he is damed right to have refused to have passed it.....sounds like you don't maintain your properties
This is my 1st one and doesn't everyone want to make money?