Thank your for your query. As per the terms of Just Answer and my professional licence, I am only able to give a generic advice in relation to your question.
As you applied under Tier 2, your Certificate of Sponsorship would have stated how long is employment with your sponsor. According to that, the Home Office has given you leave to remain in the UK until the end of September 2016. In order to avoid becoming an overstayer, you need to either apply for further leave to remain in the UK by applying under whatever category you seek and comply with the rules or leave the UK before your leave expires.
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