John Chen, CEO of BlackBerry, hit back at a T-Mobile US marketing campaign encouraging subscribers of the operator to switch to another device.

In what was described as a “great deal for BlackBerry customers”, the operator is offering the iPhone 5s with no upfront payment, on a 24 month repayment plan.

“What puzzles me more is that T-Mobile did not speak with us before or after they launched this clearly inappropriate and ill-conceived marketing promotion,” Chen wrote.

After numerous complaints from BlackBerry users, John Legere, outspoken CEO of the operator, tweeted: “BlackBerry follow up- We give our customers choices, but you don’t have to give up your #loyalty. We will continue to support.”

Thanking supporters, Chen said: “By expressing your outrage directly to T-Mobile ‎through tweets, calls and comments in the media and on blog posts, you sent a powerful message that T-Mobile could not ignore.”

He also said that for T-Mobile customers, there is “an offer in the works designed especially for you”.

Last year it was reported that T-Mobile had stopped carrying BlackBerry inventory in its US stores, with orders fulfilled centrally – enabling it to more accurately control inventory against a backdrop of uncertain demand.