1)
The verses did not mention a Bris between Ben Hadad and Basha. And if there was a Bris, why should Ben Hadad annul it?
1.
Malbim (Divrei ha'Yamim II, 16:3): He said, if you joined with Basha due to a Bris that you made with him, there is a stronger Bris between me and you, for there was a Bris also between our fathers. Basha's father had no Bris. He was a commoner! If you joined with him because he promised gold and silver to you, also I send to you gold and silver!
2)
Did Asa ask Ben Hadad to help him?
1.
Malbim (Divrei ha'Yamim II, 16:3): No. He asked only that he not help Basha, and then "v'Ya'aleh me'Alai." Basha would not be so bold to fight me alone!
