Package holiday cancellation/quality complaint

Typical aim: Refund/compensation; alternative
Be specific: dates, times, order numbers, names, promises made, and the resolution you want.
We’ll reference:
Acts & laws: Package Travel and Linked Travel Arrangements Regulations 2018
Ombudsman/Regulator: Civil Aviation Authority (ATOL) / CMA (enforcement)
Guidance: https://www.gov.uk/government/publications/package-travel-and-linked-travel-arrangements