Never,ever, ever ever ever ever book through an OTA. Never do it. This was always destined to be a disaster if anything went wrong. They have their own T&Cs they can hide behind. I will never forget (another lifetime ago) I had booked an LH flight to take advantage of a First Class fare. This is how this went down.

1. Called LH before I even called the idiots at Expedia to get the direct fare rules. Got them, took note of all rules and who I spoke with. Change fee was 300 euro.
2. Call Expedia after transferred around for a while someone finally picked up and first just keep repeating I couldn't change it. Finally agreed I could, and that it would be 900 Euro. Told them this wasn't acceptable as I had already spoken to LH directly.
3. Puts me on hold to call LH. Comes back confused and says still working on it.
4. Transfer to supervisor. Repeats everything in step 2 as though it never happened.
5. I tell them explicitly which department at LH, to whom I spoke to, and exactly how much the change fee was. (I told a white lie I had them holding the other line and would merge the call). I then told them that I was aware they are tripling the change fee to make a profit and It wasn't going to work on me. Suddenly it matched and the change was 300 euro.

They are shady and they are never worth it.