SBI CREDIT CARD DIVISION - Wrongfully billed for cancelled orders

Hi, i have been billed for cancelled orders for online purchased even after merchant refunded amount to sbi credit card. they are not solving my issue and threatening for legal notice. this is what happened.

On **-**-** i made a purchase on amazon, which converted into EMI on **th. As amazon could not delivered the product , they raised a refund request which i got credited in next month bill cycle on **-**-**. The problem is in my statement there were still EMI coming for that transaction and i paid */* EMI assuming they were my old purchases. when i contacted customer care ..they said i must pay them as emi already generated!
i assumed they will refund once i pay all * emi but they dint.. again they repeated same strategy on august **** for the transaction i have cancelled..even though i informed them not to convert that into EMI as it is cancelled transaction and amazon refunded. still they charged me... i argued that they are charging me unethically but they kept on telling those were the rules for them. In the second incident amazon refunded some *** less than full amount as one item already shipped. i told them i would pay it separately not charge me again for cancelled order. they dint listen . since then they torturing me to pay dues .

please help me with this case.. they are threatening with legal notice .i am attaching first incident mail log and statement where amazon refunded amount but they still converted amount into EMI .and call log from their recovery agents .