I would be furious!


You need the name of their bank, the transfer dates (and times if you can get them) and the transaction numbers.
I would take that info to my bank and have them call directly to track down the money. If your bank wont help you, call their bank directly.
Best case is it was just a snafu with the account number, perhaps they transposed a digit or something. These bank transfers ARE traceable with the transaction numbers so they should be doing more to help you, both their bank and yours.
Squeaky wheel often gets the grease; make some NOISE! Post openly on their social media anywhere you can.
I'm really sorry. What a nightmare! Good luck & please let us know WHEN (not if, don't take no for an answer) you get this resolved.