This look like a scam to me. Bro, application withdrawal is free.Agent told I have to pay $75 for withdraw the application the we will apply new application for work visa
Send a webform to IRCC to withdraw your application. See link below:
https://secure.cic.gc.ca/ClientContact/en/Application/Form/74
Also, send email to IRCC office in Dar es Salaam. This is their contact email a
dslam-immigration-enquiry@international.gc.ca