@Dogwood you sound a mess. I, and I’m sure all the other members, are crossing their fingers, legs and toes for you also. I totally get you can’t go through another merry-go-round again, you shouldn’t have had to of in the first place.
All’s well that ends well, do let us know how it all worked out. Go enjoy that holiday, you deserve one 
Hihi . But I wrote within a few hours. I just say its all about informing someone when you are not available. Its all about informing other 
As you would inform your parents or work when you are not available a long time.
I’m glad to know that you were able to get in contact through member support and now have their contact information and confirmation that they are coming .
@Dogwood To me, it’s still not clear why the sitter didn’t respond to your messages, but eventually only when contacted by Membership Services. Did he not receive the system messages?
I am not usually a stirrer, but something like this upsets me a great deal. They put you through dark times wondering if you still had a sitter. And then, eventually made contact when prompted by membership services. It doesn’t sit right with me.
Not uncommon for messages to be unseen / go missing / disappear from THS inbox.
Have had a similar experience recently immediately after accepting a sit - sent a couple more messages confirming our arrival time and requesting that we exchange our phone numbers . Heard nothing from HO - for a week - we then sent another a message .
This time we got an immediate reply with apologies as they had not seen either of our previous messages - but immediately responded with the information requested and we now have mobile numbers to contact them .
This is not the first time that I have had a HO say that they had not seen the messages we sent and it’s been frequently reported as an issue by various members on this forum.
However, in your situation @Dogwood I would have expected sitter to also be attempting to contact you, as it is close to the sit date . Some sitters are just more laid back about these things and happy to leave it until the last minute.
@Dogwood Had you already shared your Welcome Guide with the sitter which has your address ?
Please don’t stress, you do have 2 weeks! And I am more relieved by the fact you made arrangements with 2 close people that you can definitely count on, than anything else. At least they are on the location already and you trust them.
Do you have dogs? cats? do you live in a busy area that has paid dog or cat sitter? city? rural?
The worst that could happen is that he doesn’t show up on the day you depart. If that happened, would that be ok with your two “back up” contacts?
out of curiosity, does he know you are in the (I assume) aviation industry? Have you said anything about helping him with his flights?