HSBC Credit Card — frauds in case of balance Transfer interest rates

Hi,
I have hsbc credit card bearing no-[protected] from past 4yrs. i got calls from HSBC bank that providing Balance Transfer facility on my cards at the rate of intrst 0.99% pm (reducing) for life time . From past two yrs i applied 9 to 12 times of balance transfers with different amounts and i am paying 0.99%pm rate of intrest but from last 9months hsbc charging @3.3%pm. when i spoke with hsbc executives ,their response was that these are purchase transactions and they are charging me at 3.3%pm intrest.
i contacted so many times in this matter to call center and hsbc bank in somajiguda name called Mr.Pramod ( no[protected] but no proper response.
From the above information i want file a case aganst Hsbc for cheating their customers. I have every evidence regarding above conversation.
Plz help me in this matter.
R. naga raju mob [protected]