Too late for this year but thinking of next. I've tried saying 'Nothing', 'Please don't get me anything', 'There's nothing I need' and 'I'd prefer to just buy for the children'. I'm happy to buy small presents for adults who enjoy getting presents, but if stopping meant they'd stop for me then I'd do that. I've tried suggesting foodbank, this is ignored.
Like many, I've had a difficult year, yet my expressed wishes are being completely disregarded again. I like Christmas, I just don't want anything.