Sandler Sales training. If you can get your company to sponsor it, go to it. Tell them "I took your feedback and am researching ways to develop. Would you be interested in sending me to this training?"
The in person training is phenomenal. Here's a cheap book that is very valuable too. https://www.amazon.com/Sandler-Rules-Timeless-Selling-Principles-ebook/dp/B0033WSW7K