The reason she said “I did go through Turbotax” is because it’s a follow up to another question she asked in another thread. Someone here wanted to know if she used TurboTax.
I don’t know about British English, but in American English “I did go to ___” and “I did go with __” are not uncommon update sort of statements, following a conversation with someone about a place to go, or which sort of company/product they should choose; often these statements spoken begin with “Oh,”. In this case she chose to use Tubotax to file her taxes.