My local mate has been with Standard Chartered for 10 years, every 2 years locks in another 2 year contract with them and they give him some cashback between 1%-2% each time. He laughed at me and made me feel like an idiot when I told him I've been with SC for 10 years and I missed out on 5 rounds of cashback. He just calls his relationship manager and sorts it out.
I finally did it last year, I needed a solicitor because I had mortgage insurance tied to my mortgage so had to redo the whole lot (even if it was SC to SC). But I managed to get 2.1% back and redraw extra up to 50% of my property value which gave mea lot of extra cash back, and then they gave me an offset account so can dump the money straight into there and payback the mortgage straight away. So another loophole to get even more cashback, I actually got about 4% back with this loophole.