As Sirius is pointing out, first you need to find out if you are eligible to change sponsors in country and without the 12 month cooling off period outside of the UK.
If you are able to change sponsors, the company would need to obtain a sponsorship license. Yes, there are lawyers who can help with this. The company has to meet a list of criteria. There would be considerable time and expense on their part. Are they willing to wait and spend the money?