In example 1 it will be necessary to obtain a note from the local doctor showing that it is medically necessary to return home earlier or later than planned. The assistance company must also give their agreement.
If you have already contacted the assistance company regarding a major incident there is no further action to take other than for the customer to file a claim on his return for the proportion of his 'lost' holiday.
In example 2 above customers may feel they have a claim for a proportion of the lost holiday because they cannot ski or participate in planned / pre booked activities. Unfortunately this is not something underwriters will cover, however they would be able to claim under the ski pack section if wintersports cover was in place.