txn and pos reversed failed

(Hyderabad)on december 5 i went to a supermarket bigbazar for purschase of items ,after all the things i collect and at the time of billing & payment i gave him a mastercard for the payment of the total amoun. 3000, first time he swipe it and ask to type the pin and again swipe it and ask the pin to type ,after i type the pin he said server is down payment cant be done...but the transaction is successfull the amount is debited from my account two time and he told me that the amount is not credited to the merchant "future value retain ltd hyd" but i got messages on my cell phone that amount i credited to "future value retain ltd" and they refuses that they did not...after half and hours one transaction is reversed where as second is still withheld it did not reversed...i unable to took those product..all they gave that a transaction slip "txn failed,sale reversed" they said that with in 24hours your amount will be reversed for damn sure...after 24 hours i approach to them again they gave new reason and said amount will be surely reversed in yours account and also gave written latter and said lodge a complaint in home branch (BANK)and said your amount will be reversed in minimum 45 days.but as par my bank account status, is shows that money i credited to merchant, and they are not accepting this and misbehaving by saying do what ever you can..all they are doing is not good,they are tricking the customers and there money,all there are blaming on server, banks ,they are not accepting there mistake which knownly done by there employ...after argueing they took me to near by bank by saying we will reversed you are money there come with us, all they did there is,again the same thing said money will be credited with in 42hours and then i approach to the same bank manager and said whole story ,he said them let them shop or els give us our money but they did not agree with that, and again manager said atleast give them a letter of 4 5 day "if money did not reversed we will repay then" they agrees with this but after going back to market all they handed me is 45days letter,fedup there non scense i walk out there with letter and next day went to my bank and submits the letter and other statement for complaint..the bank manager only said we can only do is lodging a complaint,and lets hope money can reversed. Kindly please advice me how should i complain about them if my money did not reversed Into my account Or what should i do. Thank...