Bangladesh - Dhaka - Hilltribe permits in Rangamati/Bandarbancu

I land in Bangladesh on the 29th and have a general route planned. From Dhaka I will take "the Rocket" and explore the Kulna area for a few days. Then I want to make my way to Chittagong to see the beach and the hill tribes.

My question:

Does anyone know the current process of acquiring permission to enter Rangamati/Bandarban? I have been posting questions on the Bangladesh couchsurfing board and the members have been lovely but I have been getting conflicting answers.

One local posted:
"I suggest you go to both Rangamati (maximum 2 days needed) and parts of Bandarban (upto Boga Lake perhaps)! In any case, you need a Hill Tract permission from DC office (Chotteshari Road, Chittagong)..free of cost..takes 10 mins."

And a CSer messaged me:
"It is a very good idea to arrange this as soon as possible, that is if you are going there of course. Takes about 7 days to complete."

What was everyone else's experience. I am just shooting random messages everywhere hoping my trip doesn't experience any huge problems.

thank you

As a individual traveler , to visit Chittagong hill track it is still remain same that you have to ask permission from Chittagong , specially for Bandarbans , you have to mention the boga lake visit in the permission paper, go in any working day from Sunday to Thursday specially in the first half, it about half and hour to get the permission.
Normally the tour operator , the arrange the remission atleast week ahead .

Super easy. Goto the district commissioners office in Chittagong, takes 20 minutes and is absolutely painless. Funnily, despite checking in and out at the army post going upto Banderban, a Bangla friend of mine received several calls to check i was safe and had left the hill tribes area safely as i had given his number on the form.