@Fiona343 This kind of scenario is why hosts should always try to keep communication with guests within the Airbnb messaging system. That way, it's easy for Airbnb to check the message stream to see that a guest is trying to extort a host for a good review, or any other thing. So you shouldn't be texting with guests unless it's just for something inconsequential like them letting you know they're running behind schedule and may be a half hour late for check-in, for instance. If a guest texts you the kind of thing you're experiencing, it's best not to answer by text, but to move it to the message stream "Hi XXX, I wish to keep our communication on the Airbnb messaging system, so please respond here, rather than texting." If they respond by sending another text, don't answer it. S ome guests are hip to not wanting Airbnb to see what they are writing, which is why they try to take it to texting or phone calls.
And you can also try to get them to reiterate what they said by text on the messaging- "Hi XXX, so just to confirm as per the text you sent, you'd like a refund of XXX amount and if I agree to that, you offered not to leave me a bad review?"