For those who might be interested, I got another response from the Square data controller.


They basically have said that they cannot alter personal data due to technical limitations in their system..
They also pushed to ask if I'm asking for erasure of my data (deletion of my account). Which is frustrating as I've repeatedly stated I would like my data to be rectified, not erased, as per my rights under GDPR.

If it is a breach of data regulations, I'm not sure that technical limitations is a very good argument.

They have ignored my question about what personal data is being used by the new payment processor so round the merry-go-round we go again, woo~