How do I use Promo code? Why can't I talk to someone directly?

I am a 1st time Book client trying to get/use a promo code listed on Google. How do I do this? I've tired of typing this request on the ROVER "help" site. It's hard to beleive all the "great reviews" when the owner pays arbitrary fees to Rover so sitter can get clients, owners pre pay with NO REFUNDS and cannot talk to anyone about the coupons offered online.