Hello Mr. Amitabh
You can easily get other medicines from medical store other than Buprenorphine.
However, initially it will be difficult for you since after stopping buprenorphine, you may have withdrawal symptoms for few days but they can be taken care of by other medicines.
You need to consult a psychiatrist for the change on treatment plan.
Next Steps
if admission to a setup is not possible for you, kindly consult a psychiatrist.
Health Tips
As you have used heroin for around 20 years, it will take some time to make you completely free from it. you need to keep your motivation strong and you will be able to overcome all the difficulties.