A Christchurch woman duped a hotel into disclosing private details of a client who had spent the afternoon in a room with her boyfriend.

A woman has laid a complaint with police after a hotel manager allegedly gave her personal details to the partner of the man she was having an affair with.

The Nelson woman, who won't be identified, said she went to police after being sent almost 100 abusive texts messages. She will also lay a complaint with the privacy commissioner.

The woman who sent the abusive texts left an iPhone in her boyfriend's car and used the Find My iPhone app to track him after he refused to go on a weekend getaway to the Bluff Oyster Festival with her.

Last week, she approached the manager at the Quality Hotel Elms in Christchurch, and told him a "sob story" about a lost dog which she said had last been seen there.

The dog had in fact been taken along to the secret tryst by the cheating partner.

The woman allegedly persuaded manager Chris McLaughlin to release the details of the cheating partner's mistress, and video footage of the pair together.

On the day the pair were tracked to the hotel, the cheating partner's mistress said she received a call from the man urging her to get out of the hotel room.

"I felt just terrified, I kept looking over my shoulder the whole time I was driving away from the hotel," she said.

"I was furious, the minute I realised she had my details, I lost it."

McLaughlin said the hotel was "taken advantage of" by the Christchurch woman.

"As a hotel we acted in good faith with pure good intentions to willingly want to assist someone who appeared distressed and in desperate need... her story was very, very strong," he said.

"Unfortunately it has turned out to be a bit of a love triangle."

McLaughlin did not confirm whether he released the Nelson woman's personal details but he said it was "disgusting" how the Christchurch woman had duped him and would be more cautious if a similar situation presented itself again.

The woman who tracked her partner said she did "spin the guy a yarn about a lost dog" because she was desperate to find out where the man she had spent three years in a relationship with had been.

"It was so gutting when you think you are in a complete relationship with some and making plans for the future and you find out they are doing the same with another woman."

The Nelson woman also said she had also been in a relationship with the man for three years.

After the hotel allegedly released her information, she received almost 100 "abusive and hurtful" text messages from the Christchurch woman, who also posted on her business social media profile.

The woman admitted sending the texts, saying "you pull out all the punches and do the stupid texts and then move on."

She said she was sorry for the way she reacted and would apologise to the hotel manager who she lied to.

Police were investigating a harassment complaint from the Nelson woman, a police spokeswoman said.

The Nelson woman is also working on filing a complaint to the privacy commissioner.

She will complain on the grounds that Principle 11 of the Privacy Act was allegedly breached by the hotel.