Iiam Shotton

I have tried and it advises no agents available I was told to send them in by paper but I still have no idea what I need to do they are more than 4 years old

I have nearly 20k owed in tax but I need to complete self assessment from 2014 and 2015 but it won’t allow me to do this online, was hoping someone could advise what I would need to do. Do I need to request 2x sa200 forms any help is greatly appreciated