Grandchildren and Christmas gifts

Perhaps they should have, could have, got you something for Christmas, but they didn't. If it were me, I'd have been upset, but wouldn't have sent a note telling them so! Just don't bother to get them much (or anything at all) if you can't afford it, or if you expect something in return. Christmas was 6 weeks ago now, and you sound rather bitter.

I would never in a million years write to someone to tell them they should have given me gifts

As polite/gracious as your GCs replies were, its hardly a surprise that your letter obviously prompted them ranting to their mum who sprung to their defence, perhaps she shouldnt have, after all they are adults. But you cant have thought that your letter wouldnt prompt drama?

I’m on my own now with a low income

Why on earth are you still giving two adult women pocket money then ?

I would not have sent them a message, they are old enough to decide whom to buy presents for. If you see upset by not getting one back, just don't do it. I don't give to receive, but I do like an acknoledgement, if when they got to 21 they didn't, I would just say I am not sure you get what I send you so will just send a card and give a present when I see you.

Does it matter ? I wouldn't dream of putting anyone under an obligation to give me a present just because I gave them one. I wouldn't expect anything in return whatsoever.

Do you see your GC often? Are they students? If so, they may be short of money. My own children only bought my parents presents when they moved near us in the last few years of their lives. I had to prompt them to do that to be honest. They tended then not to buy their brothers presents as they didn't have much money. You are in danger of upsetting your GC I'm afraid.