My DS grandma is driving me nuts too, split from her son 4 years ago, however, have remained friends for DS.
She explained to me just before xmas, that her DS [my sons dad] had suggested he might wait for the january sales, and take son to get his xmas presents then 
[Iknow this was her suggestion to him], that annoyed the hell out of me, thinking to myself, what if I decided to do that, DS would wake up to fookal xmas morning. She then countiued to say she has told him "no problem, probably get more for the money etc", I was to stunned to say anything.
Seeing as I am his mother, I would have thought it was my decision to make, hope this makes sense
Its now 30th decemeber, DS hasnt even received a phone call of his father all over xmas
Pisses me right off, because I know if I mention something, his mother would make some bullsit story up, to cover his selfish fat arse