This article has been updated to include a statement from T-Mobile.

An email blast issued by T-Mobile last week, offering BlackBerry users a chance to upgrade to an iPhone, has been met with an angry response from BlackBerry CEO John Chen. 

Chen voiced his outrage over the promotion in a blog post, saying he’d not been told about it in advance. 

“I can only guess that T-Mobile thought its ‘great offer for BlackBerry customers’ would be well received. T-Mobile could not have been more wrong,” Chen said.

Chen thanked the BlackBerry user community for its loyalty and willingness to take T-Mobile to task. He promised to soon announce a special offer for BlackBerry users on T-Mobile.

Chen sounded disappointed with T-mobile but also hopeful that BlackBerry’s partnership with the Un-Carrier could continue.

“I would like to remind you that our long-standing partnership was once productive and profitable for both BlackBerry and T-Mobile. I hope we can find a way forward that allows us to serve our shared customers once again,” Chen wrote.

Following the email from T-Mobile, many angered BlackBerry customers took to Twitter to complain, and T-Mobile CEO John Legere acknowledged their dissatisfaction with personal responses to individual Twitter users.

On its website, T-Mobile currently appears to only offer the BlackBerry Curve 9315 (new and refurbished) and a refurbished Q10. But a T-Mobile spokesperson indicated the carrier also offers the BlackBerry Z10.

“Customers can purchase some of the latest BlackBerry devices from T-Mobile – including the Q10 and Z10 that we have carried since they launched. They can buy and direct ship devices from more than 3,000 T-Mobile retail stores and as an additional courtesy to our BlackBerry customers, we will begin offering free expedited shipping of BlackBerry devices by Friday. Customers can also bring unlocked BlackBerry devices to T-Mobile. We are happy to be a BlackBerry partner and apologize for any confusion,” a T-Mobile spokesperson said in a statement.