Screw the £300.
Work out how much money Moya has cost you in lost duties, lost OT, lost SA, lost night turns and lost hours for everybody.
Think of the bullying management culture she has nurtured and encouraged.
Think of the piles of undelivered parcels and mail clogging up your office last Xmas, not because of strike action but because of poor management and the complete collapse in the standard of service offered to customers.
Moya has been in charge for 1,225 days so far. That £300 works out at less than 25p per day of putting up with her making your life, and that of your colleagues, significantly worse. That wouldn't get you a lousy cup of coffee from one of the overpriced vending machines that have replaced the closed down canteens in most offices.
Mull it over during your next 20 minute break before your 5 hour delivery.