Hello

I have had one extension on a Non O visa due to health reasons, is it possible to get a second with another letter from a Doctor.

Thanks

It may be possible if you cannot travel, but will be down to immigration. Here are the official rules from Police Order 777/2551:

2.25 In the case of medical treatment or convalescence or to look after a patient:

Permission will be granted for a period of not more than 90 days at a time.

(1) Confirmation and request has been made by a physician responsible for the treatment. The Physician must describe the details of treatment and advised that the illness is a barrier for travelling.

(2) In the case of looking after a patient, confirmation and request has been made by the physician responsible for the treatment or by an embassy or consulate.

(3) Patient Carer, except parents, spouse, children, adopted children or children of spouse, shall be granted no more than 1 extra person.

Immigration will have the last say and can have their own doctor take a look at you. In general, if you are a patient at a major hospital they will have liasons with immigration and can take care of the extension for you.