Firefox (Mozilla) doesn't provide support via phone. There is only this official support forum.

Do a malware check with several malware scanning programs on the Windows computer.

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  https://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  https://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  https://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  https://support.kaspersky.com/viruses/disinfection/5350

https://support.kaspersky.com/viruses/utility

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

How did you contact them, or did they contact you?

Help us safeguard Mozilla’s trademarks by reporting misuse {web link}

For over a year, an epidemic of Fake Update Notices have been popping up all over the place. https://support.mozilla.org/en-US/kb/forum-response-i-found-fake-firefox-update

. Whenever you get a message / popup that offer support;

DO NOT USE ANY OF THE PROVIDED LINKS OR ANY PHONE NUMBERS ! !

Such messages are only Spam that could lead you to Fake Support. Not only can they damage or hack your system, they charge you to do so.

You can report such a site at; Google Report Phishing Page {web link} which is the same when done while on site by going to Help > Report Web Forgery

Thank you for sharing your add-on information. You have an extension that looks a little sketchy: Manual Update 7.0.0. Could you disable or remove that one, and anything else you do not remember personally installing for a good reason?

You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. Then cast a critical eye over the list on the right side. Any system extensions that Firefox installs on its own are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious? If in doubt, disable.

Sometimes a link will appear above a disabled extension to restart Firefox before the change takes effect. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

My Firefox was very out of date. I installed several updates and the adware ceased. Thanks!

whatwhat said

I thought this was Firefox support, but this man from "Global Experts online" didn't seem legit after a few minutes looking into my machine. ... . At least Microsoft has legitimate support lines!

A actually relevant link that has not been posted yet is https://support.mozilla.org/en-US/kb/avoid-and-report-mozilla-tech-support-scams

Companies that do provide one on one support by phone, chat, or email are generally for Paid for products like antivirus clients or Microsoft Windows OS's for example.

Mozilla does not have the resources to do call centres for one on one support by phone, chat, or email episodically since it would be for free for a free product since Mozilla does not charge for anything. They also do not work with any third-party support sites that claim to do support for the desktop Firefox web browser.

Support for desktop Firefox is here at https://support.mozilla.org/en-US/questions/ , at Mozilla newsgroups, on IRC https://wiki.mozilla.org/IRC with support channels like #sumo and #firefox. Another place is the popular long running independent forums.mozillazine.org forum.