I'd suggest that you message the Marriott Bonvoy Lurker III , as this sounds very unfortunate but only that an escalation would give the desired result. The agents are probably unable to assist, though they should have their own escalation route. I would actually take the long phone calls as an example that they are really trying hard to make this right for you.

[It is easy to say in hindsight "never cancel a reservation until you have the new one booked", but I realise in this case your number of points made that impossible and it seems you did all the right things by calling up. The first agent scenario isn't ideal for sure.]