Am I responsible for the costs here?

[Shouldipayornot]

Willing to accept I'm the unreasonable one hear but want a sense check.

I've previously used a tradesperson who does good work at an affordable rate, but who is also incredibly disorganised. Think not turning up on the day with an array of excuses, poor communication etc. Revews of him all essentiaĺly say the same.

A while ago he came round to quote for a few jobs, he also suggested additional work which we were tempted by. After chasing for the written quote FOR MONTHS, he finally responds with a figure for all the work, it's good, we like it. We book him in for three weeks' time.

Now, a week and a half away, we've realised the additional work he suggested we dont actually need or want, however we still want all the original requests and there's other work we are after which could be done during the time he would have been doing the other thing.

So, I message him this. He responds effectively saying its too late as he's already got all the materials in for the extra job and has already prepped them all and its cost him hundreds.

We categorically dont want the work done but he's pushing to still do it. Or, I think wants us to pay for materials.

Here's the thing, I'm almost certain he's making this up. Firstly, given his disorganisation, it's almost laughable that weeks in advance he would have diligently been prepping for our job.

Secondly, he didnt do a thorough set of measurements for the work (just rough ones), thirdly, previously he didnt work like this, he did it all on-site, fourthly I've googled the raw materials cost and I cant see how it comes close to what he has suggested, fifthly, i would have thought if he was going to start prepping everything, he would have checked in just to confirm before spending his own money.

However, because I had aggreed three weeks prior to the work, I know this also reflects badly on me. But AIBU in this situation to not continue with the extra job/be responsible for the cost of materials?

What was the extra work?

Thanks for all the feedback and advice.
It's now sorted in a way that suits all parties. Work is going to be adapted but using materials 'purchased', so no one is left out of pocket.

I completely take on all YABU responses and the reasons why. And, just to be clear, my initial query was very much based on my experiences with this person prior, and how they work. I do understand that, ordinarily once you've committed, you've committed. It just seemed odd in this situation.

Imagine a flaky friend who's always late/cancels at the last minute, chastising you, the one time you say 'actually can we re-organise'. It felt a bit like that.

Anyway, it's sorted now and in a diplomatic way.

Ask for the receipts to be provided within 24 hours. And also state categorically that the price you will pay will be dependent on him turning up to do the work on x date. And for each day he’s late, you’ll deduct X. He’s unreliable and you’ll likely be left with a half finished job

Ask for the receipts for the materials and check them diligently.