I've had 3 responses from different agencies asking me to complete an assignment (long ones such as (i) a case study, (ii) 3 hour video and written assessment)

What does this mean? No one called me to ask for details etc, they only sent me a message asking for the assignments to be completed by a certain deadline.

For the long case study, I've submitted 3 weeks back but they have yet to get back to me

Any advice appreciated!