I have been asked (as a last resort) to have my DDs friend (Anna, say) back after school on friday just for 2ish hours as it's the only time my DF can squeeze in a hair appointment. This is absolutely fine - the girls' get on well together and I'm always happy to help a friend in need. In fact its lovely that they're getting together out of school as theres been a few friend issues - another litle girl (Bella) who had previously played nicely with DD and Anna, and had been welcomed at our house (where she was terribly badly behaved and I think some things of DDs went missing, but I try not to think the worst) has tried to drive a wedge between DD and Anna to the point where DD is constantly, nastily excluded by Bella. I understand Anna is not blameless in this, and I have spoken to DD about true friends and tried to encourage other friendships. She seems to have settled a bit now but it has taken a year.The nastiness that Bella displays is unbelievable when she thinks she isn't being watched, but she plays the game is a very likeable child when she wants (or needs) to be iyswim? Anna is lovely to DD when they are one to one.
So I was quite looking forward to friday and was certainly willing to extend the play time if it was all going swimmingly.
The problem now is - Anna's mom has just texted and said "Oh I forgot that Bella is coming for a sleepover on Friday - you don't mind picking one more of them up do you - I'll be back by 6 at the latest and grab them both and go?" 
So, now I have to endure Bella excluding my DD at her own house and having DD feel crap when they go off and have a sleepover at Anna's house, making her feel even more of the spare part.
AIBU to think that this is a bit of a mickeytake of my friend (who knows there have been issues - but not the extent of them)?
(PS - sorry have namechanged just in case)