Prority for wheelchairs/rolaters on buses in wheelchair spaces

For all disabled people to be able to travel on buses. I was asked to leave a "first" bus the other week with my husband because the driver felt the bus was over crowded and although there was a seat beside the stairs, he said I could not sit there as it was again health and safety regulations. As we got off, my husband noticed, there was in fact a space beside a buggy that was already there