Wrong full termination of employement

Hi, I am seeking legal advisory and suggestion to counter the wrong full termination done by employer. I was working as HR Manager from last 5 months with small Healthcare company with setup of 50-60 employee. One of the vendor who supply us small orders like gifts, mementos etc has done fraud of submitting bills of shop which he doesn't own. He claims it is his Uncle shop and used his Bills consist of Valid VAT and Tin No. All the material he has provided is genuine and reasonable cost.When i went to that Shop mentioned in bill, Shop name and VAT etc and genuine but the owner denied that goods is delivered from his shop and he doesn't know any vendor who deals with us. In last order that vendor send me the bill through email of Rs 4000/- for submission but when i got print it was blank bill without any cost in it. I call him and he said by mistake he send the sample Bill. My Boss got that print out and he alleged me of submit fake bills to the company. I denied all the allegations which were baseless and told him this is sample bill which vendor sent by mistake. The Vendor was ready to come down to this office to give clarification on fake bills and sample bull he has submitted but my boss didn't listens and said either resign or will terminate. I refused to resigned on this baseless allegation, and send email to senior Management at US. To which next day I got termination letter followed by notice from lawyer. I am wondering when vendor is at fault for submitting the fake bills, and when there is no due diligence to verify the vendor Establishment, then why i am sacked for it. My boss didn't give opportunity to hear my side and randomly asked to resign. This is his high handness atttitude and anarchism. Since this is small organization there is not level to escalate the issue and grievance handle mechanism. I wrote to higher Management , CEO of the company in US but they will are investigating the issue and will let us know and next day i got termination letter. I am seeking legal aid and suggestion to handle this case and seeking appropriate advice, where i am at no fault and facing such humiliation. My work and performance was very well recognized by every one in the organization even global team. There is history if this organization that they hire and fire people in similar manner and allegations. My personal belongings and Laptop is also confiscated by them and didn't allow to enter office. I have approval of all my transaction from all the relevant authorities including finance which they are not allowing to handover. Please suggest what legal action and respond to their notice i can send. regards Jas. k