Type D student visa not being processed

Hello everyone,

I am new to here and I've been browsing the forum for answers for some time. I hope you can help me in any way.

Briefly, I'm a Turkish citizen who applied for a Type D student visa for Belgium 3 weeks ago as I got accepted from KU Leuven to do my Master's. A friend of mine who applied for the same visa, on the same day, same hour, and from the same place, got his visa 2 weeks ago. Some other friends of mine also received theirs within a week.

As I contacted the Embassy and VFS, I've learned that the Foreigners' Office is holding my documents and that they are the decision makers. When I had a chance to get them on the phone, they told me that it could take up to 2 months for my application to be processed.

Now, I already missed the orientation week, but I am also missing the first week of the classes. The situation is uncertain. And all I'm asking is: Why is this happening?

My only guess is, as I was an Erasmus student in Belgium back in 2015, I received the same visa and also the temporary residence card. I dug deeper with my Belgian friends to find out if I did something wrong during my stay. All I could find is that I didn't return my temporary residence permit back to the commune, because I wasn't aware I had to, until 2 days ago. I thought including the card in my files would actually benefit me, which also the lady at the VFS counter encouraged me to do so.

I need any crumble of advice. I have a studio contract done for a year, and my classes are starting on Monday. I never had a visa problem in my life and my passports are filled with Schengens. I really appreciate any kind of help.

Thank you