We had same situation except HO phoned us to cancel. I asked her to put it in writing on the THS site so I had proof and could make an insurance claim if needed and she very willingly did that for me. I also took screenshots of our conversations both on THS and on WhatsApp to back up my claim.
My claim has been submitted and I have no doubt that we will be compensated for the two nights we had to pay for accommodation. (We were able to find a replacement sit for the rest of the days.)