With your qualifications, I think the issue is largely that this is not the time of year for hiring teachers in kindergartens.
Having been bitten in the past, I am very wary of language centres who are always hiring: it means they can't keep their staff because of poor pay and conditions.
As a former teacher, I would say start looking for jobs that will start in 2nd semester (after Christmas or Chinese New Year), in international kindergartens. You won't get a visa for an assistant teacher position, but I think your chances as a class would be OK in some of the kindergartens, and you should get at least 10K a month more than the current offer.
It will also be better for you if you do not have a prior visa refusal against your name from the current offer.