Liability for the unpaid loan

I was jailed for 4 months for not being able to pay a loan from a Dubai bank since I've lost my job in 2011.

After my release, I tried looking for a job but was unsuccessful, so I went back to my home country when my visa expired but still the bank is sending emails and threatening me and wants to collect money from me.

Now that I am back here in Dubai, they threatened to file a ban against me and told me that I cannot get my visa renewed if I will not pay them.

Can the bank do such THING? I already have accepted the punishment of serving jail time since during that time I didn't have a JOB and was totally broke. What can I do so that they will stop harassing me?

What does the law say if someone had served the sentence for a bouncing check case?

Thanks and hoping to be enlightened.