Brother the question of which is right and wrong is wrong itself. That is because all the shariah laws can be implemented only when you have power , you have khilafat. Without which you cannot apply them.
When Muhammad SAW was praying in Mecca , where there no idols there ? There were . He could not do anything about that. This shows that even when prophet is present , unless he has administrative power he cannot implement certain things.
Those scholars and Muslims who say Mortgage is wrong , ask them have they devised any alternative way ? I can point out to several things that is going on wrong against shariah , but what can be done ? Individually we all Muslims but we living under secular laws , this is kufr in itself.