A short note is enough
Suppose you topped up from Dhaka using bKash, then in the f11 contact card write the subject, user ID, and time, and the support team will quickly understand what happened
Callbacks usually go in the queue after the message; if written in plain language, the answer also comes quickly, and you do not have to explain again and again
Start from the Help Center
First, check the f11 Help section; often login, APK installation, and payment questions are there
If you do not get a reply, you may request a callback; that is better, because you do not have to write the same information twice
Which channel to write
Write questions related to bKash, Nagad, and Rocket clearly in one line; if you have a transaction ID, include it
Chat, email, and callbacks all work, but for urgent login issues a concise message is most effective
That is how f11 Support is organized quickly; in the next section see how long you can realistically wait