Structural engineer made incorrect RJS calculations and refuses to amend them

[NewbieOnHolidays]

We are knocking down two walls downstairs, hired a structural engineer to perform two RJS calculations. Engineer was provided with the exact lengths of the openings that we need and the floor plans. We received the report with specifications for the two beams and required lengths. Before ordering the beams we sent the screenshot of our order to the engineer asking to double check that it is all correct, got confirmation, ordered beams. Now builder is saying beams are too short as the engineer only added 15cm to the widths of the openings in his calculations while 15cm should have been added on both sides of the beams (I.e. + 30 cm was needed in total making the beams we have too short for the job).

When we questioned the engineer he claimed it wasn’t his responsibility to calculate the correct lengths, but rather the builder who is knocking down the wall was supposed to do the measurements on site and add 2*15cm then do the order. Engineer is refusing to do anything further, not even offering an apology, suggested we maybe order small beams and wield them to the ones we have to extend them;))

what would you do?

What a nightmare. Did the builder and engineer not talk to one another? I think our architect dealt with it when we knocked through.

My structural engineer said he wouldn't do the lengths of the beams, only the sizing (and the supports necessary), the lengths are up to the installer.

Just looked at my previous paperwork and on mine it states (in capitals for emphasis) that the contractor to ensure final measurements on site. A quick google suggests this is common.

I think the builder should have known and ordered the correct length. I don't think I ever had an engineer specify the length, just the size and supports.