My state refund was supposed to be sent to the IRS to go towards what I owe in federal but it has not. The IRS keeps sending me collection bills with interest fees.

We are not aware of any such option in Turbotax. Generally, if you have a refund, you have three choices: (1) have the refund returned to you as a direct bank deposit, (2) have the refund mailed to you as a check, or (3) have the refund applied to next year's return. Oh, I guess you can have the refund applied to some sort of debit card (a sort of direct deposit), but I am not as familiar with that program as the others here probably are.

So you need to go look on your 2018 state tax return (I assume you kept the pdf or a printed copy) and see how your state refund was handled (this is normally towards the end of the main tax form for the state). If you find that you accidentally applied the refund to next year's state tax return, you will need to do a search for the "Department of Revenue" for your state and then call and ask them what your options are. In fact, you may have to call them anyway to find out if they know what you did with your refund.

NOTE: use the search string "Department of Revenue" even if it happens that your state's taxing agency has a different name; I have found that such state websites appear to have tags as Department of Revenue even if they have different names in practice (such as the California Franchise Tax Board), so they can still be found.