Just an added comment - take it how you wish:
If I had a shopper call me and say that they needed their scheduled shops changed because they lost their camera's battery, I would certainly help them the best I could.
However, I would also consider the excuse as a lack of organisation and professionalism on the shopper's part and hence tread carefully with that shopper as far as assigning important shops.
IOW, if I were that shopper, I would consider every means possible to performing the shops before calling the MSC for a re-schedule.
Sounds like the "dog ate my homework" excuse.