Immigration wont issue a COE

I was hired for a teaching position back in November 2015 that was going to start in April 2016, I received a COE and work visa, then in March 2016 the School wanted a new contract (more work hours, no more money). The school canceled the contract and my visa. In June I get another teaching job apply for a new COE but this time the school says that immigration said to call the previous employer and that they wouldn't issue a COE. Is there some way of finding out if immigration has a ban on me or something?

You need to contact immigration. Since your last COE and visa were cancelled (not expired), this may be a red flag with them.