Police in the north of the city said they had dealt with at least seven incidents in the past week.
An 85-year-old man in Maryhill was targeted by a crook claiming to be carrying out roof repairs last Tuesday. He accompanied the OAP to the bank to withdraw a large amount of cash.
But bank staff became suspicious and the conman was arrested and is awaiting trial.
Bogus callers also targeted at least three homes in Broadholm Street, Possilpark, on the same day.
They said builders nearby had found problems with a nearby gas main. However, the men were denied entry to homes.
And as we reported, a 90-year-old woman was robbed of more than £200 she had planned to spend on Christmas presents that same day.
Posing as an "electricity company" worker, the thief tricked his way into the grandmother's home in Balornock, Glasgow, and stole two purses containing her bank cards and more than £200 she had withdrawn from her bank.
Last Thursday and Friday there were three further incidents, two in Sanda Street in North Kelvinside where the bogus callers were also turned away from the homes.
However, on Thursday a man managed to get into the home of a 72-year-old woman in Craigbo Drive, Summerston, after telling her he was carrying out building work.
He then stole a small amount of cash.
Inspector Gordon Bennett, of Maryhill police, said: "There has been a spike in incidents in recent days.
"We want to remind people that if they are not expecting a caller, then do not let them into your home.
"Do not feel as if you are being rude to someone by asking them to call back another time.
"You can then call the company or the police to check the legitimacy of the caller.
"The good news is the message does seem to getting through to some people because we have had a number of incidents where bogus callers have been unable to get into homes."
It follows a theft in Dykebar Avenue, Knightswood, where a 98-year-old woman was robbed by a man impersonating a parcel delivery man.