Welcome to the Community Forum and thanks for your post. I'm sorry to hear that you are experiencing a problem with your handset sending one text and the receiver receives multiple texts.
Please try the following checks/resets:
Is your handset is displaying the correct date and time settings? If not, please update settings.
Perform a manual network selection on your handset. If you need assistance with this, please see our following online Help & Support page for handset settings: Virgin Mobile phone support then under Network click on How do I manually search for mobile networks?
Reset the message centre number: Under Messaging click on How do I find and edit the Message Centre number?
Try your SIM card in a different handset. Are the multiple texts still being received?