The period excuse would be believable if it weren't for the fact she went radio silent straight away and then resumed contact an hour later. Too much of a coincidence, rather than a double booking she bounced you for the punter already in her gaff, who may've been a regular or just offered her a wedge. If she's a popular girl with good services then all the more likely that a greedy fucker would try to extend. You are an unknown to her and until you actually knock on her door you could be a flake; a reasonable if disrespectful practice by SPs who have to deal with all kinds of nutters.
Next time tell the girl you don't mind period play and you're coming anyway. IF she blows you out then post the neg straight away so other punters booked for the day are forewarned. They might well come back and say they aren't being waved off, in which case we'll better know her true colours.
If she reads this site or one of her fluffies sees this then she'll already know who you are so your re-booking may or may not be in jeopardy anyway. Best you can do is tell everyone who this SP is.
Most SPs I've encountered work despite their period, they might tell you once you arrive or as you're about to get into a particular act either as a courtesy or a means to avoid delivering services after taking your cash. I've had "honest" girls call me hours before so I don't bother travelling; some have been genuinely surprised and apologetic when we both find she's come on as we're getting into things; others have agreed services and then let me find out for myself, presenting what they think is a quandary, if we agree to continue you know she's a keeper, if she tries to avoid services then refuses to refund a curtailed encounter then you know she's an opportunist that needs to be outed and binned.