Leaned Mr.Tripathi has given valuable suggestions. Please follow the advice.
It is believed that you have with you in your record:
-the examination report/Prescripttion/lab reports, scan/x -ray reports, bed rest advised by the doctor for the entire period of your leave, medical bills of the medicines taken by you etc and the doctor who has treated you is medically qualified/specialist to treat the medical disorder you are suffering from.
-Leave application/s submitted by you to the company and its acknowledgment of receipt.
-Date, time ,phone number with STD code from which the call was made, and your phone number at which call was received.
If you are stressed and have psychosomatic symptoms tension/depression...due to ongoing circumstances, of your sickness, being bedridden, threats by the employer (name of employee, designation???), you should consult your doctor, and psychiatrist for complete treatment.
You should also send a gentle representation in consultation with elders in the family/experienced and competent people known to you/lawyer or law firm, to your appointing authority/MD/Company Secretary, and explain all the events in chronological order, date wise, and mention specifically that you had applied for medical leave, and requested that it may be sanctioned even without pay, and you are instead being issued threats by Mr/Ms...........that civil and criminal cases shall be filed against you as per orders of the highest management for no fault at your end, and no leave shall be sanctioned. And that a cheque bounce case shall be filed against you. You can ask them that they can get you examined by a specialist at your residence at their cost and consequences.
If you are medically unfit to join the duty, duly certified by a specialist, company can not sue you but of course can decide to terminate the employment/find your replacement.
Company also know the trends in the industry, and is probably seeing it as an attempt to wriggle out of bond.
Be straight forward and if asked produce record of your sickness.
If still the company decides to sue you, you shall need the services of a competent lawyer.