Dear [Manager Name],
I would like to thank you for the recent promotion which encompasses a great deal of faith in my abilities. I deem this decision as a sign of trust that I recognize and plan to justify in every feasible way. Having said so, I couldn’t help notice that this move was not coupled with an adjustment to my pay. As you already know, the new position involves a greater deal of responsibility and additional duties.
I have full belief in the compensation and benefits policies followed in the company, and I could only think that this happened due to an error somewhere in the process.
Thank you.
Sincerely,
[Your name]
[Date]