What else can I do to maximise my chances of getting interviews?
You need to make sure that your cv is working for you. To this end, the cv needs to include as many sales based achievements as it possibly can. Sales Managers want to see evidence that you are a high performer, somebody who will exceed their sales targets consistently. Less bluster, more achievements! In short, there is nothing else that can be done other than be persistent, don’t give up, and a successful career in medical device sales is there for the taking.