my son and dil do not do cards, they haver never done this, not even to there own kids, i did not get a birthday card for a couple of years, it was usually a text the night before to tell me my present was in the bank, always the same at christmas, even my dad said to me last sunday not to send a card, but i did, being house bound at the moment i had to do it using funky pigeon, i have to remind them to message using face book to other family members or at least send an email. i think it is just the way people are now, royal mail is not like it used to be, i have sent items next day delivery and they have got lost. tell your mum you sent the card and wished them happy birthday and tell her that is the end of it, and if she keeps going on about something that is not your fault then you are going to leave or hang up if it is a phone call, i have said this to my mum on the phone as she is the type that just goes on and on and i am almost 60.