Help breaking out of a do...while loop in powershell

Hello Powershell Experts,
I’m once again stuck on something simple.  I have created (with significant help from this community) a small script that basically allows me to input a department and collect a list of users in that department along with their titles, and their mailbox size.  This part is working fine.  What I would like to do is put this into a loop so that a help desk person could run the script and collect the information for multiple departments.  My Powershell skills are embarrassingly elementary and I’m having problems setting up the loop correctly.  I think I want to use the Do…While loop as part of my script.  The code below lets me run the report for more than one department:

$RunReport = 'y'
Do {
$ReportLocation = "D:\PreMigrationReports\'$Department'.txt"
$Department = ""
$Department = Read-Host "For which department do you want to run the pre-migration report?"
$Users = Get-user -Filter {Department -like $Department}
$title = foreach ($user in $Users) {select-object title}
$Results = foreach ($user in $Users) {
    Get-MailboxStatistics $User.samaccountname | `
    Select-object `
    @{n="User";e={$_.DisplayName}}, `
    @{n="Job Title";e={$user.title}}, `
    @{n="Mailbox Size (MB)";e={$_.totalitemsize.value.ToMB()}}
    } 
Write-host "The pre-migration report for '$Department' has been saved to '$ReportLocation'"    
$RunReport = Read-Host "Do you want to run the pre-migration report for another department?"
}
While ($RunReports = 'Y')

The issue I’m running into is I don’t know how to break out of the loop.  I tried something like the following, but I keep getting asked if I want to run the report for another department.

$RunReport = 'y'
Do {
$ReportLocation = "D:\PreMigrationReports\'$Department'.txt"
$Department = ""
$Department = Read-Host "For which department do you want to run the pre-migration report?"
$Users = Get-user -Filter {Department -like $Department}
$title = foreach ($user in $Users) {select-object title}
$Results = foreach ($user in $Users) {
    Get-MailboxStatistics $User.samaccountname | `
    Select-object `
    @{n="User";e={$_.DisplayName}}, `
    @{n="Job Title";e={$user.title}}, `
    @{n="Mailbox Size (MB)";e={$_.totalitemsize.value.ToMB()}}
    } 
Write-host "The pre-migration report for '$Department' has been saved to '$ReportLocation'"    
$RunReport = Read-Host "Do you want to run the pre-migration report for another department? Y/N"
If ($RunReport -eq 'N'){Write-Host "Your departmental pre-migration reports are ready for retrieval."}
}
While ($RunReports = 'Y')

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I know this is very elementary stuff and I apologize in advance for having to ask, but I’ve tried everything I can think of and I’m just not getting it.  Thanks in advance.

Nick