RSJ Building regulations

No it is not necessarily correct, but it is difficult to give a definitive answer with such minimal information. Things that would need to be considered in structural terms are the direct loading onto any beam over the opening - this will determine the size of the beam required. Part of the calculation process will provide the end reactions (the amount of load transferred from the beam to each of the ends supporting the beam) from this information the requirement for padstones and the suitability of the structure beneath, to take the loading coming on to it can be determined. If all these can be resolved adequately then the amount of buttressing and resistance to wind loading will need to be taken into account. Sometimes it is necessary to introduce steel columns at each end to form a 'goalpost' situation (may need additional concrete to the foundation to support these. Other times it may require rebuilding of the supports in class B engineering bricks or 7N/mm2 blockwork. In my experience (30 years) the answer is rarely 'no', it is just 'not that way' but 'this way' with this 'cost implication' I have frequently designed 6m+ openings for extensions so if you are told it can't be done ask why? then ask how the problem could be solved, then finally, can you afford the solution? If the consultant says there is no solution regardless of cost then you need another consultant!

No , He's pulling the wool over your eyes. Get a good engineer!!!!