Microsoft dumped Gold status partner Comantra following accusations it fleeced its customers in support call scams.
The Indian company was accused of calling Microsoft customers and charging as much as $300 to remove what it claimed were malware infections on their computers.
It has denied the allegations.
Support workers were said to have called customers on behalf of Microsoft and claimed their computers were infected with malware.
"Following an investigation, the allegations were confirmed and we took action to terminate our relationship with the partner in question and revoke their Gold status," Microsoft said in a statement.
"We were made aware of a matter involving one of the members of the Microsoft Partner Network acting in a manner that caused us to raise concerns about this member's business practices.
"There are no circumstances under which we would ever allow partners or any other organisations to pose as Microsoft. We view matters such as these extremely seriously and take immediate action if such behaviour is brought to our attention and found to be the case."
Comantra's director Rajesh Bajaj said Microsoft's move was "not expected" and denied it was scamming users.
He said the online reports were "negative marketing" from competitors.
Bajaj said Comantra staff read sales script that included a computer "health check", but denied staff were claiming customer machines were infected with malware.
"Quality is now the biggest priority, which we are focusing on," Bajaj said, adding Comantra was speaking to Microsoft to get the decision overturned and regain its partner status.