A stalker bombarded his ex with 300 calls in a single day after their relationship ended, Lincoln Crown Court was told.
Callum McCall had already been given a restraining order banning him from contacting hairdresser Natalie Bradley after being prosecuted for harassment.
But within 48 hours he was contacting her again via Instagram.
Rebecca Coleman, prosecuting, said that Ms Bradley blocked him but he continued to harass her.
Miss Coleman said: “He went onto the page of her business and changed the information to say it was permanently closed and would soon be becoming a chip shop. He changed the photograph to include one of himself with Natalie.
“On January 28, Natalie received over 300 missed calls from a private number.”
Miss Coleman said Ms Bradley, who lives in Wales, continued to receive more calls which she recorded.
“All of these calls were recorded. They were disturbing and threatening in their nature. He told her he was going to make life unbearable for her. He told her he would be having the last word. He said she would have to have security wherever she goes.”
In one phone call McCall threatened: “I can scar you for the rest of your days.”
Miss Coleman added: “The defendant also made excessive calls to her hair salon and on February 9 it resulted in her having to unplug the line for four hours.
“The defendant had been in a relationship with the victim. They met on Facebook in November 2016 and in May 2017 they met in person and began a relationship. That ended two months later.”
McCall was subsequently convicted of harassment of Ms Bradley and in January this year he was given a restraining order banning him from contacting her.
McCall, 26, of Doughtys Court, Lincoln, admitted two charges of breach of the restraining order. He was jailed for eight months and given a new five year restraining order banning him from contacting Natalie Bradley.
Judge Simon Hirst told him: “You caused her untold misery. You know perfectly well that I have to pass a sentence of immediate custody.”
George Wills, in mitigation, said McCall suffers from mental health problems including anxiety, depression and OCD.
“It seems to be that he was going through what can be described as an episode and things were coming to a head. He says he was not lucid when he was awake and didn’t really know what was going on
“Provided his mental health can stabilise and he has some assistance from probation he can can go back to being the law abiding citizen he was before all of this.”