Hmm, I would have signed before I came or at least gotten an offer letter. If you started work without a contract and they offered you less there isnt really any proof of that.

You also cant work here on a visit visa, nor is it legal for the company to make you pay your own visa fees. If you are here on a business visa you can work but your time here is limited. If you are on a business visa longer than a month (not sure if the time period has changed or not) you will need an exit permit to leave.

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"Diplomacy is the art of saying 'Nice doggie' until you can find a rock - Will Rogers"