@Anthony82....... I am possibly having a similar issue in that I can log onto my listing if I am at my computer at home but, if I try and log on from another computer or another location the system tells me my username or password are not correct, despite the fact they are the exact same details I use for each.
You will need to contact Airbnb helpdesk on the UK number you will find previously on this thread.....Just scroll back and you will get to it, and I am sorry that it has taken 19 hours for someone to respond to you! I can appreciate this is a serious issue for you and you did deserve a prompt reply!
I hope it all works out for you. Cheers.....Rob