Beep - only sorry I hadn't read this sooner, but if someone gives you verbal agreement (assuming this was without the clear priviso of it having to be confirmed in writing at a later date), then that is good enough for any employment tribunal in the UK - I would have stuck with it, and face the consequences when you got back.
If they fired you, let me tell you you'd have won at a tribunal hands down because a Judge will look at who is being reasonable and who has acted unreasonable .............and since you initially had permission from you boss and she was WELL aware of your plans, then your company has acted VERY unreasonably indeed !!

...a hundred times more so since you also were arranging a wedding too, let alone a holiday !
Ohh, their treatment of you has so made me mad...even though I am an employer myself ! As has already been said very short sighted indeed because I expect your motivation at work is pretty zero, and likely to be so for a very long time. In my book people can come to work and do a job and get paid...or they can come to work and do a VERY good job and get paid ...either way you pay the same...but the results are very different.
Reading between the lines though it seems the fault lies with you boss, because she had OK'ed it and then I think somewhere up the chain they have said no..... leaving her to furiously back pedal in my opinion.
NO WAY should she becoming to your wedding after that, because even if she was in the wrong in giving you the verbal permission, she should have stood the ground for you, and taken the wrap herself (instead of which she lies about knowing the what date it was etc.) !
Bad boss, bad company .........truly bad behaviour all round ....except from you of course, you've been more than accommodating given the circumstances !

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Good luck with your wedding plans and chin up girl.