Enquiry About Ketamine Infusion Therapy.

I've been suffering from depression for the past 3 years, and I've taken treatment from multiple different psychiatrists for the past 1.5 years. I've been put on many different kinds of medications including SSRIs, SNRIs, augmentation medicines such as Antipsychotics, Lithium etc. And Ive not noticed improvement at all. I've been scanned for vitamin / mineral deficiencies that might contribute to depressive symptoms and everything is perfectly alright except that I have hypothyroidism. My thyroid levels are back to normal after taking the appropriate dosage, but my depression hasn't been resolved. I also think Therapy won't work for me since I have absolutely no internal or external stressors or any negative thought cycles at all. The only problem I'm experiencing is an extremely low mood which prevents me from doing anything at all. I've been suggested ECT by a psychiatrist but I do not wish to proceed with that. Where In Chennai can I avail Ketamine Infusion Therapy for my condition?