Since your res is not making it to the end of the purchase process, TL is not "stealing your seats". What is happening is that there is an inconsistency in the booking engine, so you see a fare as available when it really is not. All sites do a final check at the source to confirm the fare is available for sale. I get it all the time when I want to jump on what looks like a hot price seen on multiple sites and am unable to book it on any site no matter how hard I try or how many times I clear my cache.
If you need the flight, book it at the rate that will sell. If you decide to wait it out, it may take up to 72 hours for the mismatch to clear.
Sorry for the hassle............