SIL is bossy and arrogant and likes to think she knows better than anyone else. She takes pity on us poor idiot plebs and generously distrubutes at any opportunity her pearls of wisdom on how me, DP, and pretty much everyone should organise their lives, finances, relationships and children (despite her having a whacking wage so no money worries, having been engaged five times, and having no children). She pisses us off and tries to interfere all the time, she and DP are not close and luckily she lives a few hours away so we don't see her often.
Christmas is always a stress with her because she tries to organise everyone and sort out big extravagant pressies that we can all club in for, etc. This year she announced that she doesn't have as much money due to a job change so could we set a limit of £10 each which is great and something we've been suggesting for years.
Our pressie from her arrived the other day in an enormous box, very heavy, with a message that she'd changed her mind and blown the £10 budget and got us something else that she saw and knew we needed.
It's a microwave (other relatives have told us, we haven't opened it yet). We have a microwave. In fact when she visited a month ago we had a conversation about how little we use the microwave and were thinking of moving it from the worktop into a cupboard, so why on earth buy us one? 
It's embarassing that we've all stuck to the budget SHE demanded this year and yet she's just blown it on an expensive gift. It's bemusing that we had a convo with her on how little we use the one we have. I'd never buy someone something so large for their house without checking first that they want one and what kind/colour/size would be best. DP and I hate waste and do not see the need in replacing things that work perfectly well.
We don't know what to do really. We can't give it back to her but neither of us want it in the kitchen as it'll piss us off when we look at it.
It probably all sounds very pathetic and ungrateful being cross that someone's bought us an expensive gift but it's more that it represents the looooong history of SIL thinking she knows better than everyone else (eg when we announced that I was pregnant recently everyone was really happy for us apart from SIL who lectured DP for half an hour over how we should get married before the baby arrives, even though anyone who knows us knows that marriage is not a priority for us)
WWYD? Anything or nothing? I am clouded by pregnancy hormones and the automatic red mist that seems to descend whenever I'm involved with SIL.......