When we moved 7 years ago we had a bit of a palaver with not only the buyers of my wife's house but also who we bought from. We were stuck in a bit of a chain of idiocy.
The buyers were from Scotland (no chain) and had been used to different rules and tried even up to the week before completion to threaten with pulling out and/or trying to reduce their offer, even though we were in the hands of solicitors etc at the time and nothing was holding up the process technically, they were just impatient even though the chain wasn't stretched.
One Sunday whilst I'm cooking dinner they turned up unannounced at the house as they "wanted to measure for curtains". The wife was quite perturbed by this and wanted to tell them to go away in a slightly impolite manner, but I smoothed it over just to make sure they weren't going to be complete loonies about the sale as they were already being niggly and grumpy (mostly the wife of the couple) for no reason.
Switching sides to the buying side for us, we dealt with a couple that had already put in an offer on a bungalow and were set on moving to a local town a few miles over to be closer to family etc. After viewing the house which was a stretch for us and actually over budget, we put in a lower offer than asking price. The declined that offer, so for the sake of £5K we offered asking price.... they said they wanted to think about it???
Er...... the wife was straight onto their estate agent and said "They have one day to accept the asking price, you know, the price they want, otherwise it's off the table". We were a little gobsmacked that they had to think over getting an offer that met the asking price they wanted for their house.
Luckily they had a quick change of heart, the sale eventually went through after a couple of months and we moved in early October 2018.
On the day of the move..... baring in mind we're still in a chain, with the house we need to move into needing to be vacated before we can move in and keys be exchanged etc, our buyers were still threatening to pull out if they weren't in by 1pm. This lady, the husband was a meek wet fish tbh, obviously wasn't smart enough to realise she was now in a totally legally binding contract/monies paid situation, so I told our house movement company to take their time with it and take extra (slow) care when loading our stuff into their vans!
I kept my estate agent updated as to expected ETA's and "she" was sat at the estate agents offices from 10am waiting for the keys.

Even our estate agent told her that she'll be sat for a few hours due to the above move out, move in scenario. Eventually about 2:30pm I dropped of our old house keys to the estate agent and luckily the "buyer bitch" wasn't there as she'd had to go get some lunch after waiting around.
We got moved in fairly quickly and I spent the next week unpacking boxes etc as I was on holiday from work (not much of one tbh) but we had noticed that there was a kettle left in the kitchen which was either left behind so we could make a cuppa or more probable, left behind by accident, so we put it to one side for the previous owners. Two days later the phone rings and it's the estate agent asking if there had been a kettle left behind and we informed them that one had and we'd put it to a side for them, to which the estate agent asked if we could drop it off to them so the previous owners could pick it up. Whilst the estate agent premises weren't too far away (about 8 miles) it wasn't a town we went to very often or needed to, so we said it would probably be a few days before we could get there as we both worked full-time.
Another couple of days passed and the estate agent rings again asking for the kettle, to which we repeated that yes we still have it but we're not making a special 16 mile round trip for someone who left their kettle behind and will drop it off when we get chance, but if they want to come by and pick it up they can do.
The following day we get a knock at the door and a young lad is stood there and sheepishly asks if we have a kettle for our buyers. It turns out he's the nephew of the couple who sold the house and he apologised profusely for the hassle and agreed it wouldn't have harmed them to wait or buy another kettle/boil a pan.
Luckily that's been the biggest hassle since moving (although my wife's car got stolen this past February from our drive), but the TLDR is people are ******** at times and can't make their minds up even over the simpleist ****.
Good luck in buying/moving.