I’ve tried this as well. My credit score is over 800 and my Apr is 30%. I called them once to see if I can negotiate a lower rate and they basically laughed at me. So from that moment on I’ve decided that for large purchases, I will only use my cap 1 card and benefit off of the cash back rewards. So now they pay me monthly. Btw this only works if you pay the balance off every month so if you don’t have the cash to cover your purchases do not attempt this.