I don't know if I'm here too late to give a reply. Actually I faced the same problem a year back. My previous employer wasn't giving release. They only gave me the NOC. That means I can come back with a new visa, anytime (no need to wait for 2 years). Normally some companies dont give release as they ll face some problems when they apply for new visa. So what I did was, I made an unofficial meeting with the new employer and explained the fact. And they were ready to issue a new visa for me. I gave my passport copies and NOC and the copy of the exit stamp on the passport once I exit the country. In less than one week I got a new visa and came back here.
I don't know actually ur problem can be fixed like this or no. But may be u can have an idea about what's happening as long as this is my real experience...
Hope u get best
Tc