O2 said it has launched an investigation into how such shocking letters, which contained free pay-as-you-go Sim cards ordered online, came to be mailed out.
The family received the letters back in August 2017 by an unknown third party but presumed they were junk mail and only recently discovered the hate messages.
"We were really saddened to come across these letters, especially having a younger child in the house who we don't want to grow up witnessing such hateful language, a spokesperson for the family said.
"It's even sadder to think that such hate speech has become normalised despite living in such a uniquely multicultural and diverse city like London," the spokesperson said.
O2 said their Sim card postage and printing was managed by a third-party partner and was automated and assured the family that it would be working with this partner to review the entire process.
The company said it "has a rigorous data-cleansing process in place to prevent any of our free products being sent to addresses with obscenities or offensive names, and so this is a rare occurrence".
"If the family decide to report this case, we will work closely with the police as part of their investigation," a spokesperson said.
"Whilst it is imperative that corporations upgrade safeguards to prevent such incidents recurring, there are broader concerns about the government not taking Islamophobia seriously," he said.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)