I have a Roca Laura 20AF boiler and would like to have an English boiler man to provide an explanation of what is what

The boiler was serviced only recently but there is a fault on the Electrical resistance (which I believe is the back-up in case the boiler fails) - see picture with a circle.  I havent yet got this fixed and would like a second opinion as in the last 2 years I get different explanations on how this boiler works depending on which man comes to service it.  In summary:  it takes a long time for hot water to flow (depending on the time of day);  I would like to know how to set the timing functions for the purpose of the underfloor heating.   There seems to be 2 timer settings - one on the ROCA Boiler (not sure if this is specific to the heating or if its for both) and the other is on a gadget called Hensel distribution box (see picture) - Not sure what this is for.   I have been told that the electrical thing on the tank (see picture) is faulty so they have disconnected it (as the electrics kept on tripping) and apparently needs replacing.  Thanks.