Originally Posted by Bukhara

In 99% of cases, it's not the person and their own stupidity but simply a lack of training and piss-poor reservation system that BA has created. Sometimes staff do not like giving a negative answer and will try and sugarcoat the response by shifting responsibility (and conflict) to check-in in the vain, often misguided, hope that they can do something

For the OP, I would imagine that it is the wheelchair that has made the difference. A fellow with wheelchair and unable to ascend aircraft steps gets a limited seat map, I believe.