My TA has done a great job but she has also given me all the info incase I wanted to change or add anything on my own. It's very easy to book things on your own. I did a few things for my last Nov trip. I go through a TA because they have cheaper
travel insurance and it doesn't cost me a dime to use them. She has 2 other ladies working with her and they watch for additional discounts or reduced prices and changes things for me. Gives me a piece of mind.
But I also double check her work, if I was in the OP position I would still keep the TA but relied on myself for the ADRs. After the trip I would let her know that I will not be referring any one else to her and I would be looking for a new TA. We're all human and make mistakes but not owning up to them or trying to make it right. I don't agree with that.
Now if money wasn't an issue for me, I would dump her eat her fees and start all over again. I know canceling with my TA I would pay $300 for my family of 4. Might be worth it.... I don't know, if she hasn't done anything to mess up your trip don't know if it would be.