Unfortunately, @Sophie398, Airbnb is anything but a fair and ethical company, as you've now discovered to your cost.
They use their vaguely worded (and often contradictory) T&Cs to wriggle their way out of meeting their legal and moral responsibilities and obligations, and to renege on their duty of care to both hosts and guests alike.
For example, they state..
7.2.1 Airbnb Payments will generally initiate Payouts to your selected Payout Method: (i) for Accommodations, 24 hours of the Guest’s scheduled check-in time (or 24 hours of 3:00 pm local time - or 3:00 pm UTC if local time is unknown - if the check-in time is flexible or not specified)
But, as with everything else, they also have a get-out clause for that...
7.2.2 Airbnb Payments may delay or cancel any Payout for purposes of preventing unlawful activity or fraud, risk assessment, security, or investigation.
So, technically, they can - and do - delay (or even cancel!) host payouts, whenever the mood takes them - as long as they throw in the words "bug" or "investigation" somewhere, they have their arses covered under their terms of service (which hosts have no choice but to agree to, in order to access their accounts)
However the FCA - or the media - might not see things in quite the same way. The European Commission has already forced Airbnb to amend several of their T&Cs (from the consumer aspect), as they were found to be unlawful, under the regulations of the jurisdiction. It's about time we, as hosts, started standing up for ourselves too, and challenging the company's abusive, exploitative T&Cs, from the service providers' (our) standpoint.
Hope you get sorted soon Sophie! There's nothing worse than being put under financial pressure, due entirely to the negligence, shady practices and dodgy dealings of others. Fingers crossed for you!