To think this in unfair of my mum?

[SpongeCake23]

My little boy of 11 months is being looked after by my in laws when I go back to work next week. They weren’t originally planning to, however they’ve stepped in for now, as our original childcare has fallen through.

Anyway, they have a prior engagement in a couple of weeks time that they don’t want to miss. My mum is visiting that week anyway, but was due to go home the day before. They asked me if my mum would do them a favour and stay that extra day to have him then (my mum doesn’t work so wouldn’t need to get back for that).
I asked her and she said no. Her reason being because she doesn’t want to look after him on her own because he’s too heavy to lift. I feel like this is an excuse and I don’t understand why she wouldn’t want to help me out. So I said my only other option is to call in sick and she said “well you’ll have to then” and when I said I was worried about how that would be perceived after just going back after maternity leave and that I don’t like lying to my employer, her response was “it’s not my problem”.
She then went on to say how ungrateful I was when I said I felt a bit upset by what she’d said. She proceeded to list all the time she’s put herself out for me and all the things they’ve done for me over the years and how selfish I am!

Now bear in mind this isn’t the first issue I’ve encountered with my mum/parents. They’ve always been very controlling and treat me/talk to me like a child. But I really thought things would change when I had my son. But it seems like they want to be grandparents on their terms which makes me sad.
They do live around 4 hours away, but both have free travel due to my dad working for the railway his entire working life.
They, especially mum constantly complain that they don’t get to see my DS enough and that my in laws are his main grandparents , but when opportunities arise to spend extra time with him, even if that is doing a favour for me, they don’t want to do it.
They’re happy visiting if it conviniences them, but don’t seem to want to put themselves out to come up and help when I really need them to (like now).

One day of childcare, Lovepoppy, one day. You'd be a piss-poor grandmother to refuse to even consider doing that.

My mother would always have my children but only if I took them to her. She does drive but can’t ever be bothered to drive to me. It’s hard when your parents don’t have your back

I can barely believe what I'm reading @pumapuma
You think that her looking after your children but asking that she does so in her own house, is 'not having your back'?

Seriously, the entitlement.

@Horatioroses I have no issue with the ask.

I have massive issues with calling her a shit grandmother for having valid reasons to say no. I have issues calling her Oh shit grandmother if she had no reason to say no. It’s tacking on to the end of a visit, it’s a big ask.

My mother Told me that she would never be a full-time care for my children. That she would help as she could on her schedule, but that I should not expect to rely on her. I said cool. Sometime she can help, sometimes she can’t. It’s not her job. I get that. And sometimes I think her reasons are a bit ridiculous, but they are her reasons and her life. I wouldn’t fall out with her or not see her because she had a manicure appointment on a day that I wanted a babysitter.

YABU, your child, your responsibility. It’s a shame for your in-laws that they have had to step-in. They probably had other things going on. Don’t people discuss childcare plans a, b and c before getting pregnant!?