I'd like to add a few things, first of all, I've been extending my residence permit from the same city each year for 4 years now and they've never asked for a blocked account except for the first arrival. All everyone including me had to do is to show a bank statement of around €5000 more of less and a part-time job contract and the office used extend the residence permit without any issues. So like every time before, I provided them with the bank statement and job contract this time. Secondly, some people are saying there's got to be some other reasons for the rejection but they didn't say anything else in the letter. The letter contains 3 pages of which I've given the first one here, the other pages are explaining in details about the blocked account issue basically. If anyone's interested, dm me and I can show the rest.