A Hamilton woman is furious after alleged weed seller took her money and didn't deliver the goods.

A cannabis smoker was so angry her alleged drug dealer failed to deliver that she called police.

But the long arm of the law could yet catch up with both the dissatisfied customer and supplier with police saying even though no pot changed hands it's still illegal to try to buy it.

Hamilton woman Betty Tamihana claims she paid $40 for what a dealer claimed was an ounce of marijuana he was selling for $60 - a fraction of the usual price.

STUFF A drug deal gone wrong turned nasty on social media.

But like most deals that seem too good to be true, Tamihana never saw the weed, or her money back and complained both to police and on a Facebook page that boasts 40,000 members.

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The bizarre case highlights how large numbers of people are buying and selling drugs via social media and police are increasingly having to monitor them.

But in this case the user came straight to them.

Tamihana told Stuff she smokes cannabis to medicate her anxiety and the drama unfolded when she approached a man she had purchased from before, to buy cannabis a second time.

"I was looking for some weed and I posted to see if anybody did drop offs and he popped up and he said that he could," she said.

"I gave him $40 and he didn't come back. I rang and I messaged him and he turned everything off. I couldn't get a hold of him," she said.

"I automatically feared the worst, that I wasn't going to get my money back or, more importantly, my weed."

Tamihana said she went to police, who asked her to record all correspondence.

She said she believed she couldn't be charged because she didn't receive her drugs, but Hamilton police Senior Sergeant Rupert Friend begs to differ.

"Yes, there is a charge of attempting to procure a drug, so just because you don't get it doesn't actually prevent you from being charged," he said.

"If you were to come and ask me for a tinnie of marijuana and I give you a tinnie of lawn clippings, you've still committed an offence, even though you haven't got drugs in your posession."

Friend would not confirm whether Tamihana had visited police, citing privacy reasons, or whether police would act on the complaint, but said complaints to police of drug deals going bad were rare.

"We quite often come across it as a disorder type job, where they are fighting, or scrapping or screaming at each other on the side of the road."

Friend had advice for drug dealers and users.

"If you're going to get involved with a criminal element, whether it be drugs or stolen property then the chances of you not getting what you want is reasonably high," he said.

"I would suggest that anybody who is planning on committing crime themselves and gets double crossed and certainly leaves themselves liable to prosecution when they come and talk to us. However, these types of things can get out of hand and become much more serious and we prefer to know about them and stop them from becoming more violent then they may already be."

Meanwhile, Tamihana's spat with her alleged dealer continues, with him demanding an apology from Tamihana for her comments online before he gives her money back.

Stuff is not naming the man for legal reasons but when contacted by a reporter he said he considered Tamihana's money a loan.

"Nah, I'm not a weed smoker, I'm actually a church boy. I've been clean for six months and haven't sold for six months."

Tamihana has vowed to never to buy weed off a Facebook site again, and is warning other cannabis users.

"They [tinnie houses] can rip us off because they know that we won't do anything, but I'm too old for all that, to be mucked around like that."