Originally Posted by
plunet
The point is that BA have to ask you for your consent on what communication channels you want to be contacted on, and in what circumstances (performance of contract notifications, regulatory, marketing, etc), and therefore who would be permitted by implication to process your personal data in each case.
That's not true though. You have the right to opt out of marketing and most companies also give a preference of communication channel but this last part is best practice rather than mandatory.
The contact in this thread relates to an existing contract/holiday and you have no rights around how BA tries to contact you about it. Whether or not using WhatsApp is a good move is a different matter.
And re the processing of personal data, if the data is deemed necessary and has been approved for 'processing' through Microsoft, Apple, Google, Samsung or whatever other email systems people use, then safe to assume it's also valid via WhatsApp.