Why isn't my 2-year-old Shopify theme automatically updated?

I don’t understand how my Shopify Theme that is 2 years old can be outdated. Why isn’t it automatically updated? I hired a Shopify expert and this is one of the comments:" You are using an outdated theme that’s not Shopify OS 2.0 compliant which means you are missing out on additional functionality, performance improvements, and a better customer experience. All of which affect your sales conversions. If you are interested, let me know and I can put a custom proposal together."

I don’t know anything and hired this expert to get my Google listings showing and they said they fixed something…but I still received notices that most products were not showing…Yet I paid $250 and they still aren’t showing! I was told that the google feed is not the right one and I should switch…Again…ALL of the backend work has been done by “Shopify Experts” and my site is still not working properly. It seems everyone does work in bits and pieces. Any suggestions short of Walking away from this money pit? @links to members whatever that means.