My complaint:
Having been encouraged by Sainsburys to take out an American Express credit card, which arrived with a Nectar logo on it, I tried to change the payment method of my home insurance, which is with Sainsburys, to this card only to discover that Sainsburys Bank does not accept Amex.
Suggested solution:
As Sainsburys are in partnership with Amex Sainsburys Bank should change their policy.
