Oh, bless their hearts. Google reps sniffing around unsolicited is like a seagull spotting a dropped chip-they're not there to help you, they're there to make sure their beak gets fed. Their "optimisation" is just a fancy way of saying we jacked up your spend on our favourite channels.
I've had them ring me up about accounts I barely remember setting up, promising the moon. Every single time I've ignored them and stuck with my own data, I've come out ahead. Can they show me one actual improvement tied to my conversions? Never. Just a lot of vague waffle about "account structure" and "audience expansion."
Trust your gut, trust your numbers. If they want to help, they can start by proving they understand your business, not just their bonus targets.