how can I fix my sime friendly format 80e boiler?

I have a Sime Super 80 so it may not be the same. Under the boiler in the pipework leading to the boiler, there should be a water tap which when turned on gently in the direction with the line of the pipe will add water to the system. [NB it is not the bleed valve which you may have].
At your own risk.

Roy
December 2009