Banks paging Robin Hood

HS says that banks want to have a right to raise a mortgage's interest unilaterally. Not all the time, of course, but only when the bank is totally fucked.

Now that's an interesting idea. Do we, the customers, also get to reduce the interest when we don't have money? Or raise the interest on our bank accounts? "Hi, it's Vera, I am a bit broke, could you pay me a 50% interest on my account instead of whatever it is now?" Cool.