Lost emails

I've submitted an application and sent the relevant information via email using the email and reference I was provided with. I keep on having to re-send the same information as SBHL 'never' received it despite me using the correct email address and not getting a 'email not delivered' notification (I even have proof of the response from SBHL thanking me for the information yet I get called subsequently saying this information is still outstanding). The application process started 18th of February 2015 and it's still not finalised yet )-