The pumps disintegrate. All Ford dealers will know this, it's no secret.

Any Ford dealer who replaces the pump will also insist that ALL the fuel lines and the tank are flushed or replaced. They will also insist on replacing the injectors.

Also it's unlikely that any Ford dealer will offer to replace the head. Although you can do it Ford guidelines state that the head should not be separated from the block - Nor do your symptoms sound anything at all to do with the head, or gasket. It's almost certainly fuelling.

Call the Ford Customer Care line on 0845 841 1111 and tell them the situation.

It's clear that they've been completely negligent, and do not know what you are doing. Do not pay them any money.