Should we have seen the structural engineers report (pillars on each side of kitchen)?

I am a structural engineer myself and get asked this question a lot. Pillars aren't required, but the cost implications are huge. The reason Pillars are required in your case could have been for a number of reasons... 1. To avoid party wall issues on joint foundations (may not be relevant) 2. If the pillars where removed the existing foundations would have to be upgraded (huge costs) 3. If the opening was bigger, the loadings at the beam bearings could have to high for the existing masonry. It is possible to remove pillars but the cost is high, 99% of the time leading to foundation works and you will have to put in a whole steel frame to deal with lateral loading. You could always check with the engineers drawings and see if they concur with what you have, but it sounds like your builder was probably following the structural engineers orders

As builders we are bound by architects engineers and building control and as so your architect or building control should have your engineers calculations as to how big your piers should be you could ask them for the calculations if you cant ask the engineer direct

You should always receive an electrical certificate for alterations to your electrical system. Minor works certificate as a minimum for altered circuits and electrical installation certificate for new circuits which are also notifiable works(require registering with local authority borough council) REF:Pillars, Steels generally sit on pillars but to see if this was avoidable you would need to discuss this with a structural engineer.

A structural surveyor should have specified size of steel, or at least building control officer agreeing with builders calculations if he is experienced in adding steel etc. check