thank you for sharing your situation with us.
As it is only 02.10.2018 and you have resigned on the 23rd of September 2018. I would suggest that you call them or maybe go to their office in order to get an answer, when they will deposit your salary.
If they still do not communicate or transfer the money, they owe you, you can send them a "Mahnung" and give them a warning that if they do not transfer the money within a given time, they are in breach of the contract they had with you and that in such a case you will be forced to take further steps.
However, I would first try to get hold of them and find out why there is the delay before using the formal and legal way.
I we could help you, if you need further assistance please do not hesitate to contact us.