HangingBasket - are you saying that the OP's neighbour was always an entitled arse, or that she is being a bit of one now?
If it's the former, I would disagree with you - it's hardly entitled behaviour to want not to be woken at 3am every night, by something your neighbour is doing - that is perfectly reasonable, imo.
However, if you are suggesting the neighbour is being a bit entitled now, I might agree - the OP has made efforts to minimise the noise the pump makes, and I think the neighbour should give it a night or two, to see if that makes a difference to whether she wakes or not, before saying she can still hear it - obviously, it can still be heard (faintly) in her bedroom, but that doesn't mean it's still going to wake her up.
Complaining about a colicky baby who's crying all evening, until late - I am on the fence about that. On the one side, if you have a colicky baby who cries, you can't wave a magic wand and change that - it will stop, in time, but until then, I bet the OP would love not to have the baby crying all evening too - that must be really difficult for her. But, from the neighbour's perspective, it must be pretty unpleasant to have a baby crying next door, until 11pm or later every night - not as unpleasant as it is for the OP, but pretty annoying nonetheless.
I think, if you have a baby who is going to disturb your neighbours every night, until late, you need to do what you can to minimise the impact on them, within the bounds of what is reasonable for your own family life - you need to compromise a bit, and the neighbour does too - they need to realise that a colicky baby is not something a parent chooses or can, in general control, that it is making life very difficult for the mum, and that the colic will settle down eventually, so maybe the neighbour could be a bit more understanding.