In case your visa is curtailed due to some reason, an urgent professional advice is very important to secure your position, and assess what alternative options are available to regularise your immigration status in UK.
One of the most common reason of visa curtail is breaching a condition of your visa. Other common reason are when Home Office believes that you have obtained your current visa or Indefinite Leave to Remain on the basis of false representation or false document. Some of the reasons for visa curtail are discretionary, rather than mandatory, and it is possible that may be some factors have not yet been considered by decision making authority or mitigating circumstances relating to the curtailment of your leave. Moreover, you may some have exceptional, compassionate circumstances, for example, a serious medical illness that will allow you to request that you be given a longer period to remain in the country.
If decision of your visa curtail is correct in your belief than you should have to make arrangements to leave the country and ensure that you do so before your leave to remain comes to an end.
If you believe that the decision of visa curtail has been made in error or the visa curtailment is incorrect for some other reasons, at your request, you can write to the decision-making authority and request to re-consider the decision through legal representative.