Former couple Rita Ora and Calvin Harris, a case study in not mixing business with pleasure. Source: Supplied EARLIER this week we brought you the news that British pop star Rita Ora was a surprise no-show for her performance at the Teen Choice Awards. At the time, rumours swirled that Ora had been forced to give up the high profile performance slot by her ex Calvin Harris, who wrote and produced her current single, I Will Never Let You Down. [...]