A cancer-sufferer said his "life has been hell" after ex-JLS star Aston Merrygold posted his phone number on Twitter - claiming it was for his bandmate Oritse Williams.
Bill Phillips, 65, started receiving texts and phone calls "every five seconds" after the singer announced his number to his 183,000 followers as an April Fool's joke.
The grandfather - who is undergoing treatment for prostate cancer - has since received more than 3,800 texts and calls from JLS fans "at all hours" hoping to contact Oritse.
Married Bill, from Hornchurch, Essex, said: "I've got girls ringing up crying at 12 at night asking why did I split up from the band. Girls have been asking 'will you marry me?'
"A joke is a joke but this is not a joke. It has made my life hell.
"I'm getting calls and texts at all hours, sometime one and two in the morning.
"The kid is most likely a millionaire - I'm not. I'm sure he thinks it is great - it's not.
"It's costing me money and grief."
JLS star Aston, 26, posted Bill's number on Twitter on April 1 in a series of tweets in which he apparently posted number for other bandmates Marvin Humes and JB Gill.
He initially wrote: "As u can all see I've decided to take the high road and not do any pranks on April fools day."
But then he posted the numbers with the hashtag #sorry not sorry, and encouraged fans to ring them with the message: "Call them if you don't believe me. April Fools finishes at 12 if you are 12. We goooooo all day over here."
The messages and calls to Bill started within minutes and are still continuing days after the stunt.
Exhausted Bill believes the 'joke' has cost him thousands of pounds in lost jobs after he was forced to turn off the phone he uses to run two of his businesses.
The father-of-two, who runs a a stadium seat installation business and is also a pest-control falconer, said: "I'm 65 and I'm not in a boy band. I'm trying to run a couple of businesses and this is impeding it.
"I've had this number for 21 years and I use it for work and clients - it is not an option to change it.
"It has cost me money. I can't get hold of my men on my mobile, I'm having to do everything from a landline which isn't easy.
"I know already of one job it cost me.
I had to turn my phone off and missed a job they wanted doing of clearing seagulls. I was first choice but they had to offer it to someone else when they couldn't get hold of me.
"This is really not what I needed," added Bill.
The JLS singer has since apologised, saying he was "veeeeeerry sorry", adding: "No more pranks from me. And if it was your phone that got the chaos then my bad! Sorry."Suggest a correction